Collecting and processing contextual attributes on a host

ABSTRACT

Some embodiments of the invention provide a novel architecture for capturing contextual attributes on host computers that execute one or more machines, and for consuming the captured contextual attributes to perform services on the host computers. The machines are virtual machines (VMs) in some embodiments, containers in other embodiments, or a mix of VMs and containers in still other embodiments. Some embodiments execute a guest-introspection (GI) agent on each machine from which contextual attributes need to be captured. In addition to executing one or more machines on each host computer, these embodiments also execute a context engine and one or more attribute-based service engines on each host computer. Through the GI agents of the machines on a host, the context engine of that host in some embodiments collects contextual attributes associated with network events and/or process events on the machines. The context engine then provides the contextual attributes to the service engines, which, in turn, use these contextual attributes to identify service rules for processing.

CLAIM OF BENEFIT TO PRIOR APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/650,251, filed Jul. 14, 2017, now published asU.S. Patent Publication 2018/0181423. U.S. patent application Ser. No.15/650,251 claims the benefit of U.S. Provisional Patent Application62/438,379, filed Dec. 22, 2016. U.S. Provisional Patent Application62/438,379 and U.S. patent application Ser. No. 15/650,251, nowpublished as U.S. Patent Publication 2018/0181423, are incorporatedherein by reference.

BACKGROUND

Middlebox services have historically been hardware appliances that areimplemented at one or more points in a network topology in an enterpriseor a datacenter. With the advent of software defined networking (SDN)and network virtualization, traditional hardware appliances do not takeadvantage of the flexibility and control that is provided by SDN andnetwork virtualization. Accordingly, in recent years, some havesuggested various ways to provide middlebox services on hosts. Most ofthese middlebox solutions, however, do not take advantage of therich-contextual data that can be captured for each data message flow onthe host. One reason for this is that existing techniques do not providean efficient, distributed scheme for filtering the thousands ofcaptured-contextual attributes in order to efficiently process servicerules that are defined in terms of much smaller sets of contextualattributes.

BRIEF SUMMARY

Some embodiments of the invention provide a novel architecture forcapturing contextual attributes on host computers that execute one ormore machines, and for consuming the captured contextual attributes toperform services on the host computers. The machines are virtualmachines (VMs) in some embodiments, containers in other embodiments, ora mix of VMs and containers in still other embodiments.

Some embodiments execute a guest-introspection (GI) agent on eachmachine from which contextual attributes need to be captured. Inaddition to executing one or more machines on each host computer, theseembodiments also execute a context engine and one or moreattribute-based service engines on each host computer. Through the GIagents of the machines on a host, the context engine of that host insome embodiments collects contextual attributes associated with networkevents and/or process events on the machines. As further describedbelow, the context engine then provides the contextual attributes to theservice engines, which, in turn, use these contextual attributes toidentify service rules that specify context-based services to perform onprocesses executing on the machines and/or data message flows sent by orreceived for the machines.

In some embodiments, the context engine of a host collects contextualattributes from the GI agents of the machines on that host through avariety of different ways. For instance, in some embodiments, the GIagent on a machine registers hooks (e.g., callbacks) with one or moremodules (e.g., kernel-space modules or user-space modules) in themachine's operating system for all new network connection events and allnew process events.

Upon occurrence of a new network connection event, the GI agent receivesa callback from the OS and based on this callback, provides a networkevent identifier to the context engine. The network event identifierprovides a set of attributes pertaining to the network event. Thesenetwork event attributes in some embodiments include a five-tupleidentifier (i.e., source port and IP address, destination port and IPaddress, and protocol) of the requested network connection, processidentifier of the process requesting the network connection, a useridentifier associated with the requesting process, and a groupidentifier (e.g., an activity directory (AD) identifier) associated withthe requesting process.

In some embodiments, the context engine directs the GI agent to collectfrom the OS modules additional process parameters that are associatedwith the process identifier (ID) that it received with the networkevent. These additional process parameters in some embodiments includethe process name, the process hash, the process path with command lineparameters, the process network connection, the process-loaded modules,and one or more process consumption parameters specifying the process'consumption of one or more resources of the machine (e.g., centralprocessing unit consumption, network consumption, and memoryconsumption). Instead of using the process identifier to query the GIagent for additional process parameters associated with a network event,the context engine in other embodiments receives all the processparameters associated with a network event in one shot when the GI agentreports the network event to the context engine.

The OS on a machine in some embodiments holds up a new network event(i.e., does not start sending data messages for the network event) untilthe GI agent on the machine directs it to proceed with processing thenetwork event. In some of these embodiments, the GI agent only allowsthe OS to proceed with processing the network event after the contextengine has collected all the needed attributes for this event (e.g.,after receiving a message from the context engine that specifies that ithas received all the process or network attributes that it needs for thenew network event).

In some embodiments, the context engine uses the process hash that itreceives from the GI agent to identify the name and version of theapplication (i.e., the software product) to which the process belongs.To do this, the context engine in some embodiments stores process hashesand associated application names/versions, compares the process hashthat it receives from the GI agent with the stored process hashes toidentify a matching hash, and then uses the application name/version ofthe matching hash as the application name and version of the processassociated with the event.

In some embodiments, the context engine obtains the process hashes andapplication names/versions from one or more network or compute managers,which may operate on another device or computer. In other embodiments,the context engine provides the hash associated with a processidentifier to a network or compute manager, which then matches this hashto its process hash records and provides the application name/version ofthe associated process to the context engine. Once the context engineobtains the application name/version associated with a network event, itcan provide the name and version attributes to the attribute-basedservice engines, which can use this information (i.e., the applicationname and/or version) to identify the service rule to enforce.

Upon occurrence of a process event, the GI agent receives a callbackfrom the OS and based on this callback, provides a process eventidentifier to the context engine. The process event identifier providesa set of attributes pertaining to the process event. This set ofattributes includes the process identifier in some embodiments. In someembodiments, this set also includes a user identifier and/or a groupidentifier (e.g., an activity directory (AD) identifier).

In some embodiments, the GI agent provides all the process parameters(e.g., process identifier, user ID, group ID, process name, processhash, loaded module identifiers, consumption parameters, etc.)associated with a process event to the context engine when it reportsthe process event to the context engine. In other embodiments, thecontext engine directs the GI agent to collect from the OS modulesadditional process parameters that are associated with the processidentifier that context engine received with the process event. Theseadditional process parameters in some embodiments are the same (e.g.,process name, process hash, loaded module identifiers, consumptionparameters, etc.) as the process parameters mentioned above for reportednetwork events.

The context engine of some embodiments augments the contextualattributes that it receives from the GI agent with contextual attributesthat it receives from other modules that execute on the host. Forinstance, in some embodiments, a deep packet inspection (DPI) moduleexecutes on the host. The context engine or another module (e.g., afirewall engine) directs this DPI engine to examine data messages of adata message flow associated with a process ID to identify the type oftraffic being sent in these data messages by the application associatedwith the process ID.

The identified traffic-type identity is today commonly referred to asthe AppID. Also, currently there are a number of DPI modules thatanalyze messages of a data message flow to generate the AppID. In someembodiments, the context engine combines the AppID that it obtains for anetwork event with other context attributes that it identifies for thisevent (e.g., by using the event's five-tuple identifier to associate theAppID with the collected contextual attributes), in order to produce avery rich set of attributes that the service engines can then use toperform their services. This rich set of attributes provides trueapplication identity (i.e., the application name, application version,application traffic type, etc.), based on which the service engines canperform their services.

Also, in some embodiments, a threat detection module executes on thehost computer along with the context engine. Once the context engineobtains a set of process parameters that specify that a process hasstarted on a machine or is sending data messages on the machine, thecontext engine in some embodiments provides one or more processparameters (e.g., process hash, application name, application version,AppID, other process parameters, etc.) to the threat detection module.This threat detection module then generates a threat level indicator(e.g., low, medium, high, etc.) for the identified process and providesthis threat level indicator to the context engine. The context enginethen provides this threat level indicator to one or more service enginesas another contextual attribute for performing services on a new processevent or the data messages of a new network event; a service engine canuse the threat level indicator as another attribute to identify servicerules to enforce.

The context engine employs a push model in some embodiments todistribute the collected contextual attributes to the service engines,while it employs a pull model in other embodiments to distribute theseattributes to the service engines. In still other embodiments, thecontent engine employs a push model for some service engines and a pullmodel for other service engines. In the push model, the context enginedistributes to a service engine the contextual attributes that itcollects for a process event or a network event with the process'sidentifier and/or the network event's flow identifier (e.g., the flow'sfive-tuple identifier). In some embodiments, the context enginedistributes to the service engine only the contextual attributes thatare relevant for that service engine's service rules.

In the pull model, the context engine receives queries from a serviceengine for the contextual attributes that the context engine hascollected for a particular process or network connection. In someembodiments, the context engine receives a process ID or a flowidentifier (e.g., five-tuple identifier) with a query from the serviceengine, and uses the received identifier to identify the attribute setthat it has to provide to the service engine. In some embodiments, thecontext engine generates a service token (also called a service tag) forthe collection of attributes that are relevant for the service engine,and provides this service token to another module (e.g., the GI agent oranother module on the host) to pass along to the service engine (e.g.,pass along in a data message's encapsulating header). The service enginethen extracts the service token and provides this service token to thecontext engine in order to identify the contextual attributes that thecontext engine has to provide to the service engine.

The context engine in some embodiments provides contextual-attributes toseveral context-based service engines on its host computer. In someembodiments, the context engine and the service engines are all kernelspace components of a hypervisor on which multiple VMs or containersexecute. In other embodiments, the context engine and/or one or moreservice engines are user space processes. For example, one or moreservice engines in some embodiments are service VMs (SVMs).

Different embodiments use different types of context-based serviceengines. For instance, in some embodiments, the attribute-based serviceengines include (1) a firewall engine that performs context-basedfirewall operations on data messages sent by or received for themachines, (2) a process control engine that enforces context-basedprocess control operations (e.g., process assessment and terminationoperations) on processes started on the machines, (3) a load-balancingengine that performs context-based load-balancing operations todistribute the data message flows from the machines to differentdestination or service nodes in one or more destination/service nodeclusters, and (4) an encryption engine that performs context-basedencryption or decryption operations to encrypt data message from themachines, or to decrypt data messages received for the machines.

Another context-based service engine in some embodiments is a discoveryservice engine. In some embodiments, the discovery engine captures newprocess events and new network events from the context engine, alongwith the contextual attributes that the context engine collects forthese process and network events. The discovery service engine thenrelays these events and their associated contextual attributes to one ormore network managers (e.g., servers) that provide a management layerthat allows network administrators to visualize events in a datacenterand specify policies for compute and network resources in thedatacenter.

In relaying these events and attributes to the network management layer,the discovery module of some embodiments performs some pre-processing ofthese events and attributes. For example, in some embodiments, thediscovery module filters some of the network or process events, whileaggregating some or all of these events and their attributes. Also, insome embodiments, the discovery engine directs the context engine tocollect additional contextual attributes for process or network eventsthrough the GI agents or other modules (e.g., the DPI engine or threatdetection engine), or to capture other types of events, such as fileevents and system events.

For example, in some embodiments, the discovery engine directs thecontext engine to build an inventory of the applications installed onthe machines, and to periodically refresh this inventory. The discoveryengine might so direct the context engine at the request of themanagement plane, or based on operational configurations that themanagement or control plane specifies for the discovery engine. Inresponse to the request from the discovery engine, the context engine insome embodiments has each GI agent on each of its host's machinediscover all installed processes on the machine, and all runningprocesses and services.

After building an inventory of installed applications and the runningprocesses/services, the discovery engine of a host computer in adatacenter provides this information to the network/compute managers inthe management plane. In some embodiments, the management plane collectscontextual attributes from sources other than the host computerdiscovery and context engines. For instance, in some embodiments, themanagement plane collects from one or more servers compute context(e.g., cloud context from cloud vendors, or compute virtualizationcontext by datacenter virtualization software), identity context fromdirectory service servers, mobility context from mobility managementservers, endpoint context from DNS (domain name server) and applicationinventory servers, network context (e.g., virtual network context) fromnetwork virtualization server, etc.

By collecting the contextual information (e.g., information from thediscovery and context engines and/or information from other contextsources), the management plane can provide a user interface to thenetwork/compute administrators to visualize the compute and networkresources in the datacenter. Moreover, the collected contextualattributes allow the management plane to provide controls through thisuser interface for these administrators to specify context-based servicerules and/or policies. These service rules/policies are then distributedto the host computers so that service engines on these computers canperform context-based service operations.

The preceding Summary is intended to serve as a brief introduction tosome embodiments of the invention. It is not meant to be an introductionor overview of all inventive subject matter disclosed in this document.The Detailed Description that follows and the Drawings that are referredto in the Detailed Description will further describe the embodimentsdescribed in the Summary as well as other embodiments. Accordingly, tounderstand all the embodiments described by this document, a full reviewof the Summary, Detailed Description, the Drawings and the Claims isneeded. Moreover, the claimed subject matters are not to be limited bythe illustrative details in the Summary, Detailed Description and theDrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purposes of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 illustrates a host computer that uses the context engine andcontext-based service engines of some embodiments of the invention.

FIG. 2 illustrates a more-detailed example of a host computer that insome embodiments is used to establish a distributed architecture forconfiguring and performing context-rich, attribute-based services in adatacenter.

FIG. 3 illustrates a process performed by a context engine of someembodiments.

FIG. 4 illustrates examples of load-balancing rules of some embodiments.

FIG. 5 illustrates load balancers of some embodiments distrustedwebserver traffic amongst several application servers.

FIG. 6 illustrates a process that the load balancer performs in someembodiments.

FIG. 7 illustrates several examples of such firewall rules.

FIG. 8 illustrates several more detailed examples of the context-basedfirewall rules of some embodiments.

FIGS. 9-12 present various examples that illustrate the enforcement ofvarious context-based firewall rule by a firewall engine.

FIG. 13 illustrates a process that the context engine performs tocollect the user and group identifiers each time it receives a newnetwork connection event from a GI agent.

FIG. 14 illustrates a process that a firewall engine performs in someembodiments.

FIG. 15 illustrates an example of such context-based encryption rules.

FIG. 16 illustrates a process that the encryptor of some embodimentsperforms to encrypt a data message sent by a VM on a host.

FIG. 17 illustrates a process that an encryption engine performs todecrypt an encrypted data message that a forwarding-element portreceives on a destination host that executes a destination VM of thedata message.

FIG. 18 illustrates a process that the encryption engine performs todecrypt an encrypted data message that includes the key identifier inits header.

FIG. 19 illustrates several examples of process control rules.

FIG. 20 illustrates a process that the process control engine performsin some embodiments.

FIG. 21 illustrates an example of how the service engines are managed insome embodiments.

FIG. 22 conceptually illustrates a computer system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following detailed description of the invention, numerousdetails, examples, and embodiments of the invention are set forth anddescribed. However, it will be clear and apparent to one skilled in theart that the invention is not limited to the embodiments set forth andthat the invention may be practiced without some of the specific detailsand examples discussed.

Some embodiments of the invention provide a novel architecture forcapturing contextual attributes on host computers that execute one ormore machines, and for consuming the captured contextual attributes toperform services on the host computers. Some embodiments execute aguest-introspection (GI) agent on each machine from which contextualattributes need to be captured. In addition to executing one or moremachines on each host computer, these embodiments also execute a contextengine and one or more attribute-based service engines on each hostcomputer. Through the GI agents of the machines on a host, the contextengine of that host in some embodiments collects contextual attributesassociated with network events and/or process events on the machines.The context engine then provides the contextual attributes to theservice engines, which, in turn, use these contextual attributes toidentify service rules that specify context-based services to perform onprocesses executing on the machines and/or data message flows sent by orreceived for the machines.

As used in this document, data messages refer to a collection of bits ina particular format sent across a network. One of ordinary skill in theart will recognize that the term data message may be used herein torefer to various formatted collections of bits that may be sent across anetwork, such as Ethernet frames, IP packets, TCP segments, UDPdatagrams, etc. Also, as used in this document, references to L2, L3,L4, and L7 layers (or layer 2, layer 3, layer 4, layer 7) are referencesrespectively to the second data link layer, the third network layer, thefourth transport layer, and the seventh application layer of the OSI(Open System Interconnection) layer model.

FIG. 1 illustrates a host computer 100 that uses the context engine andcontext-based service engines of some embodiments of the invention. Asshown, the host computer 100 includes several data compute nodes 105, acontext engine 110, several context-based service engines 130, a threatdetector 132, and a deep packet inspection (DPI) module 135. Thecontext-based service engines include a discovery engine 120, a processcontrol engine 122, an encryption engine 124, a load balancer 126 and afirewall engine 128. It also includes context-based service rulestorages 140, and an attribute storage 145.

The DCNs are endpoint machines executing on the host computer 100. TheDCNs are virtual machines (VMs) in some embodiments, containers in otherembodiments, or a mix of VMs and containers in still other embodiments.On each DCN, a GI agent 150 executes in order to collect contextualattributes for the context engine 110. In some embodiments, the contextengine 110 collects contextual attributes from the GI agents 150 of theDCNs on its host through a variety of different ways. For instance, insome embodiments, the GI agent on a DCN registers hooks (e.g.,callbacks) with one or more modules (e.g., kernel-space modules oruser-space modules) in the DCN's operating system for all new networkconnection events and all new process events.

Upon occurrence of a new network connection event, the GI agent 150receives a callback from its DCN's OS and based on this callback,provides a network event identifier to the context engine 110. Thenetwork event identifier provides a set of attributes pertaining to thenetwork event. These network event attributes in some embodimentsinclude a five-tuple identifier (i.e., source port and IP address,destination port and IP address, and protocol) of the requested networkconnection, process identifier of the process requesting the networkconnection, a user identifier associated with the requesting process,and a group identifier (e.g., an activity directory (AD) identifier)associated with the requesting process.

In some embodiments, the context engine directs the GI agent 150 tocollect from the OS modules additional process parameters that areassociated with the process identifier (ID) that it received with thenetwork event. These additional process parameters in some embodimentsinclude the process name, the process hash, the process path withcommand line parameters, the process network connection, theprocess-loaded modules, and one or more process consumption parametersspecifying the process' consumption of one or more resources of themachine (e.g., central processing unit consumption, network consumption,and memory consumption). Instead of using the process identifier toquery the GI agent 150 for additional process parameters associated witha network event, the context engine 110 in other embodiments receivesall the process parameters associated with a network event in one shotwhen the GI agent reports the network event to the context engine.

The OS of the DCN in some embodiments holds up a new network event(i.e., does not start sending data messages for the network event) untilthe GI agent 150 on that DCN directs it to proceed with processing thenetwork event. In some of these embodiments, the GI agent 150 onlyallows the OS to proceed with processing the network event after thecontext engine 110 has collected all the needed attributes for thisevent (e.g., after receiving a message from the context engine thatspecifies that it has received all the process or network attributesthat it needs for the new network event).

In some embodiments, the context engine 110 uses the process hash thatit receives from the GI agent 150 to identify the name and version ofthe application (i.e., the software product) to which the processbelongs. To do this, the context engine 110 in some embodiments storesprocess hashes and associated application names/versions, compares theprocess hash that it receives from the GI agent with the stored processhashes to identify a matching hash, and then uses the applicationname/version of the matching hash as the application name and version ofthe process associated with the event.

In some embodiments, the context engine 110 obtains the process hashesand application names/versions from one or more network or computemanagers, which may operate on another device or computer. In otherembodiments, the context engine provides the hash associated with aprocess identifier to a network or compute manager, which then matchesthis hash to its process hash records and provides the applicationname/version of the associated process to the context engine. Once thecontext engine 110 obtains the application name/version associated witha network event, it can provide the name and version attributes to theattribute-based service engines, which can use this information (i.e.,the application name and/or version) to identify the service rule toenforce.

Upon occurrence of a process event on a DCN 105, the DCN's GI agent 150in some embodiments receives a callback from the DCN's OS and based onthis callback, provides a process event identifier to the context engine110. The process event identifier provides a set of attributespertaining to the process event. This set of attributes includes theprocess identifier in some embodiments. In some embodiments, this setalso includes a user identifier and/or a group identifier (e.g., anactivity directory (AD) identifier).

In some embodiments, the GI agent provides all the process parameters(e.g., process identifier, user ID, group ID, process name, processhash, loaded module identifiers, consumption parameters, etc.)associated with a process event to the context engine when it reportsthe process event to the context engine. In other embodiments, thecontext engine directs the GI agent to collect from the OS modulesadditional process parameters that are associated with the processidentifier that context engine received with the process event. Theseadditional process parameters in some embodiments are the same (e.g.,process name, process hash, loaded module identifiers, consumptionparameters, etc.) as the process parameters mentioned above for reportednetwork events.

The context engine 110 of some embodiments augments the contextualattributes that it receives from the GI agents 150 with contextualattributes that it receives from other modules that execute on the host.The DPI module 135 (also referred to as the deep packet inspector) andthe threat detector 132 (also referred to as the threat inspectionmodule) are two such modules that provide contextual attributes toaugment those that the context engine collects from the GI agents 150.In some embodiments, a DPI module is directed by the context engine 110or another module (e.g., a firewall engine 128) to examine data messagesof a data message flow associated with a process ID to identify the typeof traffic being sent in these data messages by the applicationassociated with the process ID.

The identified traffic-type identity is today commonly referred to asthe AppID. Also, currently there are a number of DPI modules thatanalyze messages of a data message flow to generate the AppID for thedata message flow. In some embodiments, the context engine combines theAppID that it obtains for a network event with other context attributesthat it identifies for this event, in order to produce a very rich setof attributes that the service engines can then use to perform theirservices. This rich set of attributes provides true application identity(i.e., the application name, application version, application traffictype, etc.), based on which the service engines can perform theirservices. In some embodiments, the context engine 110 uses a networkevent's five-tuple identifier to associate the AppID for this event'sdata message flow with the contextual attributes that the context enginecollects from the GI agent of the DCN associated with the data messageflow (e.g., of the DCN from which the data message flow emanates).

The threat detector 132 provides a threat level indicator that specifiesthe threat level associated with a particular application that isexecuting on a DCN. Once the context engine obtains a set of processparameters that specify that a process has started on a machine or issending data messages on the machine, the context engine in someembodiments provides one or more process parameters (e.g., process hash,application name, application version, AppID, other process parameters,etc.) to the threat detection module.

This threat detection module then generates a threat level indicator(e.g., low, medium, high, etc.) for the identified process and providesthis threat level indicator to the context engine. In some embodiments,the threat detector assigns a threat score to an application running ona DCN based on various application behavioral factors, such as (1)whether it does poor input validation, (2) whether it passesauthentication credentials over unencrypted network links, (3) whetherit uses weak password and account policies, (4) whether it storesconfiguration secrets in clear text, (5) whether it can transfer files,(6) whether the application is known to propagate malware, (7) whetherthe application is purposely evasive, (8) whether the application hasknown vulnerabilities, etc. In some embodiments, the threat detector isa third-party whitelisting application, such as the Bit9.

The context engine in some embodiments provides the threat levelindicator produced by the threat detector 132 to one or more serviceengines as another contextual attribute for performing services on a newprocess event or the data messages of a new network event; a serviceengine can use the threat level indicator as another attribute toidentify service rules to enforce.

The context engine 110 stores the contextual attributes that it collectsfor network events and process events in the attribute storage 145. Insome embodiments, the context engine stores each set of contextualattributes with one or more network event identifiers and/or processidentifiers. For example, in some embodiments, the context engine 110stores the collected contextual attributes for a new process event withthe process identifier, or with a reference to this identifier. Thecontext engine then uses the process identifier to provide the collectedcontext attributes to a service engine (e.g., the process control engine122) that performs a service for the process event.

The context engine in some embodiments stores the collected contextattributes for a new network connection event with the five-tupleidentifier of the network connection event, or with a reference to thisfive-tuple identifier. In some of these embodiments, the context engineprovides to a service engine the context attributes for a network eventalong with this event's five-tuple identifier. The data messages forthis network event will use this five-tuple identifier, and hence theservice engine can use the supplied five-tuple identifier to identifythe context attributes associated with a data message flow.

The context engine employs a push model in some embodiments todistribute the collected contextual attributes to the service engines130, while in other embodiments this engine employs a pull model todistribute these attributes to the service engines 130. In still otherembodiments, the context engine employs a push model for some serviceengines and a pull model for other service engines. In the push model,the context engine in some embodiments distributes to a service enginethe contextual attributes that it collects for a process event or anetwork event with the process's identifier and/or the network event'sflow identifier (e.g., the flow's five-tuple identifier).

In some embodiments, the context engine distributes to the serviceengine only the contextual attributes that are relevant for that serviceengine's service rules. In other words, in these embodiments, thecontext engine compares each collected attribute in a set of collectedattributes (e.g., for a network event or a process event) with a list ofattributes used by a service engine's service rules, and discards eachcollected attribute that is not used by the service rules. The contextengine then provides to the service engine only the subset of collectedattributes (in the set of collected attributes) that is being used bythe engine's service rules. In other embodiments, the service enginesperform this filtering operation to discard the contextual attributesthat are not needed.

In the pull model, the context engine receives queries from a serviceengine for the contextual attributes that the context engine hascollected for a particular process or network connection. In someembodiments, the context engine receives a process ID or a flowidentifier (e.g., five-tuple identifier) with a query from the serviceengine, and uses the received identifier to identify the attribute setthat it has to provide to the service engine.

In some embodiments, the context engine generates a service token (alsocalled a service tag) for the collection of attributes that are relevantfor the service engine, and provides this service token to anothermodule (e.g., the GI agent or another module on the host) to pass alongto the service engine (e.g., pass along in a data message'sencapsulating header). The service engine then extracts the servicetoken and provides this service token to the context engine in order toidentify the contextual attributes that the context engine has toprovide to the service engine.

In some embodiments, the context engine 110 and the service engines 130are all kernel space components of a hypervisor on which multiple VMs orcontainers execute, as further described below by reference to FIG. 2.In other embodiments, the context engine and/or one or more serviceengines are user space processes. For example, one or more serviceengines in some embodiments are service VMs (SVMs). In some embodiments,one or more service engines are in ingress datapaths and/or egressdatapaths of DCNs, in order to receive access to data message flows toand from the DCNs to perform services on these data message flow. Inother embodiments, one or more other modules on the host 100 interceptdata messages from the ingress/egress datapaths and forward thesemessages to one or more service engines for these engines to performservices on the data messages. One such approach will be described belowby reference to FIG. 2.

Different embodiments use different types of context-based serviceengines. In the example illustrated in FIG. 1, the service engines 130include the discovery engine 120, the process control engine 122, theencryption engine 124, the load balancer 126 and the firewall engine128. Each of these service engines 130 has an attribute-based,service-rule storage. FIG. 1 collectively represents all thecontext-based, service-rule storages of these service engines with thecontext-based service rule storage 140 in order to simplify theillustration that is presented in this figure.

In some embodiments, each service rule in the context-based service rulestorage 140 has a rule identifier for matching to a process or flowidentifier to identify the rule to enforce for a process or networkevent. In some embodiments, the context-based service rule storage 140is defined in a hierarchical manner to ensure that a rule check willmatch a higher priority rule before matching a lower priority rule.Also, in some embodiments, the context-based service rule storage 140contains a default rule that specifies a default action for any rulecheck, as further explained below.

The firewall engine 128 performs firewall operations on data messagessent by or received for the DCNs 105. These firewall operations arebased on firewall rules in the context-based service rule storage 140.Some of the firewall rules are defined purely in terms of layer 2-layer4 attributes, e.g., in terms of five-tuple identifiers. Other firewallrules are defined in terms of contextual attributes that can include oneor more of the collected contextual attributes, such as applicationnames, application versions, AppID, resource consumption, threat level,user ID, group ID, etc. Yet other firewall rules in some embodiments aredefined in terms of both L2-L4 parameters and contextual attributes. Asthe firewall engine 128 can resolve firewall rules that are defined byreference to contextual attributes, this firewall engine is referred toas a context-based firewall engine.

In some embodiments, the context-based firewall engine 128 can allow,block or re-route data message flows based on any number of contextualattributes, because its firewall rules can be identified in terms of anycombination of the collected contextual attributes. For example, thisfirewall engine can block all email traffic from chrome.exe when theuser is part of a Nurse user group, when one firewall rule specifiesthat data messages should be blocked when the flow is associated withthe Nurse group ID, the AppID identifies the traffic type as email, andthe application name is Chrome. Similarly, context based firewall rulescan block data message flows associated with video conferences, onlinevideo viewing, or use of old versions of software. Examples of suchrules would block all Skype traffic, block all YouTube video traffic,block all HipChat audio/video conferences when application versionnumber is older than a particular version number, block data messageflows for any application with a high threat score, etc.

The load-balancing engine 126 performs load-balancing operations on datamessages sent by the DCNs 105 to distribute the data message flows todifferent destination or service nodes in one or moredestination/service node clusters. These load-balancing operations arebased on load-balancing rules in the context-based service rule storage140. In some of these embodiments, each load-balancing rule can specifyone or more load-balancing criteria (e.g. a round robin criterion, aweighted round-robin criteria, etc.) for distributing traffic, and eachcriteria can be limited to a particular time range. In some embodiments,a load-balancing operation involves replacing a data message flow'sdestination network address (e.g., the destination IP address, thedestination MAC address, etc.) with another destination network address.

Some of the load-balancing rules are defined purely in terms of L2-L4attributes, e.g., in terms of five-tuple identifiers. Otherload-balancing rules are defined in terms of contextual attributes thatcan include one or more of the collected contextual attributes, such asapplication names, application versions, AppID, resource consumption,threat level, user ID, group ID, etc. Yet other load-balancing rules insome embodiments are defined in terms of both L2-L4 parameters andcontextual attributes. As the load-balancing engine 126 can resolveload-balancing rules that are defined by reference to contextualattributes, this load-balancing engine is referred to as a context-basedload balancer.

In some embodiments, the context-based load balancer 126 can distributethe data message flows based on any number of contextual attributes,because its load-balancing rules can be identified in terms of anycombination of the collected contextual attributes. For example, thedata distribution of the load balancer 126 can be based on anycombination of user and application data. Examples of suchload-balancing operations include: (1) distributing data message flowsassociated with the Finance department on all load-balancing pools, (2)redirecting all the Finance department's traffic to another pool whenthe primary pool for this department is down to make this department'straffic highly available, and (3) making all traffic associated with theDoctor's user group highly available. In some embodiments, theload-balancing rules can also be defined in terms of collected resourceconsumption, in order to distribute traffic to provide more or lessresources to applications that consume a lot of resources on the DCNs.

The encryption engine 124 performs encryption/decryption operations(collectively referred to as encryption operations) on data messagessent by or received for the DCNs 105. These encryption operations arebased on encryption rules in the context-based service rule storage 140.In some embodiments, each of these rules includes anencryption/decryption key identifier, which the encryption engine canuse to retrieve an encryption/decryption key from a key manager on thehost or operating outside of the host. Each encryption rule alsospecifies in some embodiments the type of encryption/decryptionoperation that the encryption module has to perform.

Each encryption rule also has a rule identifier. For some encryptionrules, the rule identifiers are defined purely in terms of L2-L4attributes, e.g., in terms of five-tuple identifiers. Other encryptionrules are defined in terms of contextual attributes that can include oneor more of the collected contextual attributes, such as applicationnames, application versions, AppID, resource consumption, threat level,user ID, group ID, etc. Yet other encryption rules in some embodimentsare defined in terms of both L2-L4 parameters and contextual attributes.As the encryption engine 124 can resolve encryption rules that aredefined by reference to contextual attributes, this encryption engine isreferred to as a context-based encryption engine.

In some embodiments, the context-based encryption module 124 can encryptor decrypt the data message flows based on any number of contextualattributes because its encryption rules can be identified in terms ofany combination of the collected contextual attributes. For example, theencryption/decryption operation of the encryption engine 124 can bebased on any combination of user and application data. Examples of suchencryption operations include: (1) encrypt all traffic from Outlook(started on any machine) to Exchange Server, (2) encrypt allcommunication between applications in a three tier Webserver,Application Server and Database Server, (3) encrypt all trafficoriginating from the Administrators Active Directory group, etc.

The process control engine 122 enforces context-based process controloperations (e.g., process assessment and termination operations) onprocesses started on the DCNs 105. In some embodiments, whenever thecontext engine 110 receives a new process event from a GI agent 150 of aDCN, it provides the process parameters associated with this processevent to the process control engine 122. This engine then uses thereceived set of process parameters to examine its context-based servicerule storage 140 to identify a matching context-based, process-controlrule.

The process control engine 122 can direct the context engine to directthe GI agent of the DCN to perform a process-control operation on aprocess. Examples of such process-control operations include (1)terminating a video conference application that has a particular versionnumber, (2) terminating a browser that is displaying YouTube traffic,and (3) terminating applications that have a high threat level score.

The discovery engine 120 is another context-based service engine. Insome embodiments, the discovery engine 120 captures new process eventsand new network events from the context engine, along with thecontextual attributes that the context engine collects for these processand network events. As further described below, the discovery serviceengine then relays these events and their associated contextualattributes to one or more network managers (e.g., servers) that providea management layer that allows network administrators to visualizeevents in a datacenter and specify policies for compute and networkresources in the datacenter.

In relaying these events and attributes to the network management layer,the discovery module of some embodiments performs some pre-processing ofthese events and attributes. For example, in some embodiments, thediscovery module filters some of the network or process events, whileaggregating some or all of these events and their attributes. Also, insome embodiments, the discovery engine 120 directs the context engine110 to collect additional contextual attributes for process or networkevents through the GI agents 150 or other modules (e.g., the DPI engineor threat detection engine), or to capture other types of events, suchas file events and system events.

For example, in some embodiments, the discovery engine directs thecontext engine to build an inventory of the applications installed onthe machines, and to periodically refresh this inventory. The discoveryengine might so direct the context engine at the request of themanagement plane, or based on operational configurations that themanagement or control plane specifies for the discovery engine. Inresponse to the request from the discovery engine, the context engine insome embodiments has each GI agent on each of its host's machinediscover all installed processes on the machine, and all runningprocesses and services.

After building an inventory of installed applications and the runningprocesses/services, the discovery engine of a host computer in adatacenter provides this information to the network/compute managers inthe management plane. In some embodiments, the management plane collectscontextual attributes from sources other than the host computerdiscovery and context engines. For instance, in some embodiments, themanagement plane collects from one or more servers compute context(e.g., cloud context from cloud vendors, or compute virtualizationcontext by datacenter virtualization software), identity context fromdirectory service servers, mobility context from mobility managementservers, endpoint context from DNS (domain name server) and applicationinventory servers, network context (e.g., virtual network context fromnetwork virtualization server), etc.

By collecting the contextual information (e.g., information from thediscovery and context engines and/or information from other contextsources), the management plane can provide a user interface to thenetwork/compute administrators to visualize the compute and networkresources in the datacenter. Moreover, the collected contextualattributes allow the management plane to provide controls through thisuser interface for these administrators to specify context-based servicerules and/or policies. These service rules/policies are then distributedto the host computers so that service engines on these computers canperform context-based service operations.

In some embodiments described above, the same service engine 130 (e.g.,the same firewall engine 128) performs the same type of service (e.g., afirewall service) based on service rules that can be defined in terms ofmessage flow identifiers (e.g., five-tuple identifiers) or in terms ofcollected contextual attributes (e.g., AppID, threat level, useridentifier, group identifier, application name/version, etc.) associatedwith the data message flows. In other embodiments, however, differentservice engines provide the same type of service based on the messageflow identifiers (e.g., five-tuple identifiers) and based the collectedcontextual attributes of the data message flows. For instance, someembodiments use one flow-based firewall engine that performs firewalloperations based on rules defined in terms of flow identifiers, andanother context-based firewall engine that performs firewall operationsbased on rules defined in terms of context attributes (e.g., AppID,threat level, user identifier, group identifier, applicationname/version, etc.).

FIG. 2 illustrates a more-detailed example of a host computer 200 thatin some embodiments is used to establish a distributed architecture forconfiguring and performing context-rich, attribute-based services in adatacenter. This host computer 200 includes many of the same componentsas host computer 100, such as context engine 110, service engines 130,threat detector 132, DPI module 135, context-based service rule storage140, and context-attribute storage 145. Like in FIG. 1, the serviceengines 130 in FIG. 2 include the discovery engine 120, the processcontrol engine 122, the encryption engine 124, the load balancer 126 andthe firewall engine 128.

In FIG. 2, the DCNs are VMs 205 that execute on a hypervisor. Also, inFIG. 2, the host computer 200 includes a software forwarding element210, an attribute-mapping storage 223, a connection state cache storage225, a MUX (multiplexer) 227, and a context-engine policy storage 143.In some embodiments, the context engine 110, the software forwardingelement 210, the service engines 130, the context-based service rulestorages 140, the connection state cache storage 225, the context-enginepolicy storage 143, and the MUX 227 operate in the kernel space of thehypervisor, while the VMs 205 operate in the hypervisor's user space. Inother embodiments, one or more service engines are user space modules(e.g., are service VMs).

In some embodiments, the VMs 205 serve as data end points in thedatacenter. Examples of such machines include webservers, applicationservers, database servers, etc. In some cases, all the VMs belong to oneentity, e.g., an enterprise that operates the host. In other cases, thehost 200 operates in a multi-tenant environment (e.g., in a multi-tenantdata center), and different VMs 205 may belong to one tenant or tomultiple tenants.

Each VM 205 includes a GI agent 250 that interacts with the contextengine 110 to provide context attribute sets to this engine, and toreceive instructions and queries from this engine. The interactionsbetween the GI agents 250 and the context engine 110 are similar to theinteractions described above between the GI agents 150 and the contextengine 110. However, as shown in FIG. 2, all the communication betweenthe context engine 110 and the GI agents 250 in some embodiments arerelayed through the MUX 227. One example of such a mux is the mux thatis used by the Endpoint Security (EPSec) platform of ESX hypervisors ofVMware, Inc.

In some embodiments, the GI agents communicate with the MUX 227 througha fast communication channel (such as VMCI channel of ESX). In someembodiments, this communication channel is a shared memory channel. Asmentioned above, the attributes collected by the context engine 110 fromthe GI agents 250 in some embodiments include a rich group of parameters(e.g., layer 7 parameters, process identifiers, user identifiers, groupidentifiers, process name, process hash, loaded module identifiers,consumption parameters, etc.)

As shown, each VM 205 also includes a virtual network interface card(VNIC) 255 in some embodiments. Each VNIC is responsible for exchangingmessages between its VM and the software forwarding element (SFE) 210.Each VNIC connects to a particular port 260 of the SFE 210. The SFE 210also connects to a physical network interface card (NIC) (not shown) ofthe host. In some embodiments, the VNICs are software abstractionscreated by the hypervisor of one or more physical NICs (PNICs) of thehost.

In some embodiments, the SFE 210 maintains a single port 260 for eachVNIC of each VM. The SFE 210 connects to the host PNIC (through a NICdriver (not shown)) to send outgoing messages and to receive incomingmessages. In some embodiments, the SFE 210 is defined to include a port265 that connects to the PNIC's driver to send and receive messages toand from the PNIC. The SFE 210 performs message-processing operations toforward messages that it receives on one of its ports to another one ofits ports. For example, in some embodiments, the SFE tries to use datain the message (e.g., data in the message header) to match a message toflow based rules, and upon finding a match, to perform the actionspecified by the matching rule (e.g., to hand the message to one of itsports 260 or 265, which directs the message to be supplied to adestination VM or to the PNIC).

In some embodiments, the SFE 210 is a software switch, while in otherembodiments it is a software router or a combined softwareswitch/router. The SFE 210 in some embodiments implements one or morelogical forwarding elements (e.g., logical switches or logical routers)with SFE executing on other hosts in a multi-host environment. A logicalforwarding element in some embodiments can span multiple hosts toconnect VMs that execute on different hosts but belong to one logicalnetwork.

Different logical forwarding elements can be defined to specifydifferent logical networks for different users, and each logicalforwarding element can be defined by multiple software forwardingelements on multiple hosts. Each logical forwarding element isolates thetraffic of the VMs of one logical network from the VMs of anotherlogical network that is serviced by another logical forwarding element.A logical forwarding element can connect VMs executing on the same hostand/or different hosts. In some embodiments, the SFE extracts from adata message a logical network identifier (e.g., a VNI) and a MACaddress. The SFE in these embodiments uses the extracted VNI to identifya logical port group, and then uses the MAC address to identify a portwithin the port group.

Software switches (e.g., software switches of hypervisors) are sometimesreferred to as virtual switches because they operate in software andthey provide the VMs with shared access to the PNIC(s) of the host.However, in this document, software switches are referred to as physicalswitches because they are items in the physical world. This terminologyalso differentiates software switches from logical switches, which areabstractions of the types of connections that are provided by thesoftware switches. There are various mechanisms for creating logicalswitches from software switches. VXLAN provides one manner for creatingsuch logical switches. The VXLAN standard is described in Mahalingam,Mallik; Dutt, Dinesh G.; et al. (2013 May 8), VXLAN: A Framework forOverlaying Virtualized Layer 2 Networks over Layer 3 Networks, IETF.

The ports of the SFE 210 in some embodiments include one or morefunction calls to one or more modules that implement specialinput/output (I/O) operations on incoming and outgoing messages that arereceived at the ports. Examples of I/O operations that are implementedby the ports 260 include ARP broadcast suppression operations and DHCPbroadcast suppression operations, as described in U.S. Pat. No.9,548,965. Other I/O operations (such as firewall operations,load-balancing operations, network address translation operations, etc.)can be so implemented in some embodiments of the invention. Byimplementing a stack of such function calls, the ports can implement achain of I/O operations on incoming and/or outgoing messages in someembodiments. Also, in some embodiments, other modules in the data path(such as the VNICs 255, port 265, etc.) implement the I/O function calloperations instead of, or in conjunction with, the ports 260.

In some embodiments, one or more of function calls of the SFE ports 260can be to one or more service engines 130 that process context-basedservice rules in the context-based service rule storages 140. Eachservice engine 130 in some embodiments has its own context-based servicerule storage 140, attribute-mapping storage 223, and connection statecache storage 225. FIG. 2 presents just one context-based service rulestorage 140, attribute-mapping storage 223, and connection state cachestorage 225 for all the service engines in order not to obscure thepresentation in this figure with unnecessary detail. Also, in someembodiments, each VM has its own instance of each service engine 130(e.g., its own instance of discovery engine 120, process control engine122, encryption engine 124, load balancer 126, and firewall engine 128).In other embodiments, one service engine can service data message flowsfor multiple VMs on a host (e.g., VMs for the same logical network).

To perform its service operation for a data message flow, a serviceengine 130 in some embodiments tries to match the flow identifier (e.g.,the five-tuple identifier) and/or the flow's associated contextattribute set to the rule identifiers of its service rules in itscontext-based service rule storage 140. Specifically, for a serviceengine 130 to perform its service check operation for a data messageflow, the SFE port 260 that calls the service engine supplies a set ofattributes of a message that the port receives. In some embodiments, theset of attributes are message identifiers, such as traditionalfive-tuple identifiers. In some embodiments, one or more of theidentifier values can be logical values that are defined for a logicalnetwork (e.g., can be IP addresses defined in a logical address space).In other embodiments, all of the identifier values are defined in thephysical domains. In still other embodiments, some of the identifiervalues are defined in the logical domain, while other identifier valuesare defined in the physical domain.

The service engine in some embodiments then uses the received message'sattribute set (e.g., the message's five-tuple identifier) to identifythe context attribute set that the service engine has stored for thisflow in the attribute-mapping storage 223. As mentioned above, thecontext engine 110 in some embodiments supplies the context attributesfor new flows (i.e., new network connection events) and for newprocesses to the service engines 130, along with a flow identifier(e.g., a five-tuple identifier) or a process identifier. Thecontext-engine policy storage 143 contains the rules that control theoperation of the context engine 110. In some embodiments, these policiesdirect the context engine to generate rules for the service engines orto direct the service engines to generate rules (e.g., when ahigh-threat application runs on a VM, directing the encryption enginefor all the other VMs on the same host to encrypt their data messagetraffic). The service engines 130 in these embodiments store the contextattributes that they receive from the context engine in theattribute-mapping storage 223.

In some embodiments, a service engine 130 stores the context attributeset for each new flow or new process with that flow's identifier (e.g.,five-tuple identifier) or that process' identifier in theattribute-mapping storage. In this manner, the service engine canidentify the context attribute set for each new flow that it receivesfrom the SFE ports 260 by searching its attribute-mapping storage 223for a context record that has a matching flow identifier. The contextrecord with the matching flow identifier includes the context attributeset for this flow. Similarly, to identify the context attribute set fora process event, a service engine in some embodiments searches itsattribute-mapping storage 223 for a context record with a matchingprocess identifier.

As mentioned above, some or all of the service engines in someembodiments pull the context attribute sets for a new flow or newprocess from the context engine. For instance, in some embodiments, aservice engine supplies a new flow's five-tuple identifier that itreceives from the SFE port 260, to the context engine 110. This engine110 then examines its attribute storage 145 to identify a set ofattributes that is stored for this five-tuple identifier, and thensupplies this attribute set (or a subset of it that it obtains byfiltering the identified attribute set for the service engine) to theservice engine.

As described above, some embodiments implement the pull model by using aservice token to encode the attribute set for a new message flow. Whennotified of a new network connection event, the context engine 110 insome embodiments (1) collects the context attribute set for the newevent, (2) filters this set to discard the attributes that are notrelevant for performing one or more services on the flow, (3) stores theremaining filtering attribute subset in the attribute storage 145 alongwith a service token, (4) provides the service token to the GI agent250. The GI agent 250 then causes this token to be passed to the serviceengine(s) in-band (e.g., in a header of the data message that theagent's VM sends to a destination) or out-of-band (i.e., separately fromthe data messages that the agent's VM sends to a destination).

When the service engine gets the new flow through the SFE port 260, itsupplies this flow's service token to the context engine, which usesthis service token to identify in its attribute storage 145 the contextattributes to supply to the service engine. In the embodiments that theSFE port does not provide this service token to the service engine, theservice engine first has to identify the service token by searching itsdata stores using the flow's identifier before supplying the servicetoken to the context engine.

After identifying the contextual attribute set for a data message flow,the service engine 130 in some embodiments performs its serviceoperation based on service rules that are stored in the context-basedservice rule storage 140. To perform its service operation, the serviceengine 130 matches the received attribute subset with correspondingattribute sets that are stored for the service rules. In someembodiments, each service rule in the context-based service rule storage140 has a rule identifier and an action parameter set.

As mentioned above, the rule identifier of a service rule in someembodiments can be defined in terms of one or more contextual attributesthat are not L2-L4 header parameters (e.g., are L7 parameters, processidentifiers, user identifiers, group identifiers, process name, processhash, loaded module identifiers, consumption parameters, etc.). In someembodiments, a rule identifier can also include L2-L4 header parameters.Also, in some embodiments, one or more parameters in a rule identifiercan be specified in terms of an individual value or a wildcard value.Also, in some embodiments, a rule identifier can include a set ofindividual values or a group identifier, such as a security groupidentifier, a compute construct identifier, a network constructidentifier, etc.

To match a received attribute set with the rules, the service enginecompares the received attribute set with the associated identifiers ofthe service rules stored in the context-based service rule storage 140.Upon identifying a matching rule, the service engine 130 performs aservice operation (e.g., a firewall operation, a load balancingoperation, an encryption operation, other middlebox operation, etc.),based on the action parameter set (e.g., based on Allow/Drop parameters,the load balancing criteria, encryption parameters, etc.) of thematching rule.

In some embodiments, the context-based service rule storage 140 isdefined in a hierarchical manner to ensure that a message rule checkwill match a higher priority rule before matching a lower priority rule,when the message's attribute subset matches multiple rules. Also, insome embodiments, the context-based service rule storage 140 contains adefault rule that specifies a default action for any message rule checkthat cannot identify any other service rules; this default rule will bea match for all possible attribute subsets in some embodiments, andensures that the service rule engine will return an action for allreceived attribute subsets. In some embodiments, the default rule willspecify no service.

Multiple messages can have the same message identifier attribute sets,e.g., when the messages are part of one flow that is associated with onecommunication session between two machines. Accordingly, after matchinga data message with a service rule in the context-based service rulestorage 140 based on the message's identified context attribute set, theservice engine of some embodiments stores the service rule (or areference to the service rule) in the connection state cache storage225, so that it can later use this service rule for subsequent datamessages of the same flow.

In some embodiments, the connection state cache storage 225 stores theservice rule, or a reference to the service rule, that the serviceengine 130 identifies for different message identifier sets (e.g., fordifferent five-tuple identifiers that identify different data messageflows). In some embodiments, the connection state cache storage 225stores each service rule, or reference to the service rule, with anidentifier (e.g., a flow's five-tuple identifier and/or a hash value ofthe flow's five-tuple identifier) that is generated from the matchingmessage identifier set.

Before checking with the context-based service rule storage 140 for aparticular message, the service rule engine 130 of some embodimentschecks the connection state cache storage 225 to determine whether thisstorage has previously identified a service rule for this message'sflow. If not, the service engine 130 identifies the contextual attributeset for the message flow, and then checks the context-based service rulestorage 140 for a service rule that matches the message's identifiedattribute set and/or its five-tuple identifier. When the connectionstate data storage has an entry for the particular message, the serviceengine performs its service operation based on this service rule'saction parameter set.

In the service architecture of FIG. 2, the DPI module 135 performs deeppacket inspection on a data message flow at the direction of thefirewall engine 128. Specifically, when the firewall engine 128 receivesa new data message that is part of a new data message flow, the firewallengine in some embodiments directs the DPI module to inspect that newdata message and one or more of the next few data messages in the sameflow. Based on this examination, the DPI engine identifies the type oftraffic (i.e., the application on the wire) that is being sent in thisdata message flow, generates an AppID for this traffic type, and storesthis AppID in the attribute storage 145. In some embodiments, thecontext attribute sets are stored in the attribute storage based on flowidentifiers and/or process identifier. Accordingly, in some embodiments,the DPI engine 135 stores the AppID for a new data message flow in theattribute storage 145 based on that flow's five-tuple identifier.

In some embodiments, the context engine 110 pushes to the serviceengines 130 the AppID for a new data message flow once the DPI enginestores the AppID in the attribute storage 145. In other embodiments, thecontext engine 110 pulls the AppID from the attribute storage 145whenever it is queried for the contextual attributes for a data messageflow by a service engine. In some embodiments, the context engine 110uses the five-tuple identifier of the flow to identify the record in theattribute storage 145 with the matching record identifier and the AppID.

FIG. 3 illustrates a process 300 that the context engine performs 110 insome embodiments each time it is notified about a new process ornetwork-connection event. From a GI agent 250 of a VM 205, the process300 initially receives (at 305) a notification regarding a new processor network connection event. Next, at 310, the process 300 collects allthe desired contextual attributes regarding the notified event.

As described above, the context engine 110 in some embodiments interacts(at 310) with the reporting GI agent 250 to collect additionalinformation regarding a reported event. The GI agent in some embodimentsinteracts with the network stack and/or process subsystem in the VM's OSkernel space to collect contextual attributes regarding a process ornetwork event. The GI agent in some embodiments also collects thisinformation from user-space modules (e.g., a user mode dynamic-linklibrary, DLL) that operate in user-space process (e.g., a VMtool.exe) tocollect contextual attributes. On VM's using Microsoft Windows, the GIagent in some embodiments registers hooks in the Windows FilteringPlatform (WFP) to obtain network events, while registering in theWindow's Process Subsystem to collect process related attributes. Insome embodiments, the GI agent hook is at the Application LayerEnforcement (ALE) layer of WFP, so that it can capture allsocket-connection requests from application processes on the VM.

In some embodiments, the context engine 110 interacts with themanagement or control plane to collect contextual attributes, and/or toreceive records that it can examine to identify contextual attributesfor identified network or process events. In some of these embodiments,the context engine interacts with a management or control plane proxy(that operates on its host) in order to obtain data from the managementor control plane servers that operate outside of the host. In some ofthese embodiments, the context engine operates in the kernel space.

After collecting the contextual attributes at 310, the process uses (at315) the attributes of the received event or the contextual attributescollected for the received event to identify one or more policies in thecontext-engine policy storage 143. At 315, the process identifies anypolicy that has a policy identifier that matches the collectedattributes and event attributes.

Next, at 320, the process produces context-attribute mapping records forone or more service engines based on the policies identified at 315. Oneor more of the identified policies might specify that for a particularprocess or network event, a particular set of service engines need to benotified about the event (e.g., about a new data message flow), witheach service engine receiving a subset of contextual attributes that arerelevant for that service engine to perform its processing for thatevent. This operation in some embodiments involves the context enginenot including attributes that are not relevant for each particularservice engine in the subset of contextual attributes that it providesto that particular service engine.

In some embodiments, certain events might necessitate new service rulesto be created for one or more service engines. For example, when ahigh-threat application is identified on one VM, a policy might specifythat other VMs on that host might have to start to encrypt their datamessage traffic. In some such embodiments, the context-engine policystorage 143 includes policies that direct the context engine to generateservice rules for service engines under certain circumstances, or todirect the service engines to generate such service rules. For suchembodiments, the process (at 320), if needed, generates service rulesfor service engines under certain circumstances, or directs the serviceengines to generate such service rules

At 325, the process 300 distributes the mapping records and/or generatedservice rules/instructions to one or more service engines. As mentionedabove, the context engine can employ a push model or a pull model todistribute such records and/or rules/instructions. When employing a pullmodel, the process 300 in some embodiments not only performs theoperation 325 in response to a query from a service engine, but alsoperforms some or all of the operation 320 in response to this query.After 325, the process ends.

The load balancing engine 126 is a context-based load balancer thatperforms its load balancing operations based on load-balancing rulesthat can be specified in terms of not only L2-L4 parameters, but also interms of contextual attributes. FIG. 4 illustrates an example of suchcontext-based load balancing rules. These rules are used independentlyby different load balancing engines 126 on different hosts 500 todistribute data messages from different webserver VMs 505 on these hoststo different application server VMs 510, as shown in FIG. 5. In someembodiments, the hosts 500 are similar to the host 200, and thewebserver VMs 505 and the application server VMs 510 are similar to theVMs 205 of FIG. 2. To avoid obscuring the figure with unnecessarydetail, the only components of hosts 500 that are shown in FIG. 5 arethe load balancers 126 and the webserver VMs 505, with the loadbalancers appearing as service modules in the egress path of thewebservers VMs 505.

In the example illustrated in FIG. 5, the load balancers 126collectively form a distributed load balancer (i.e., a single,conceptual logical load balancer) that spans across the multiple hoststo distribute webserver VM traffic uniformly across the applicationserver VMs. As further described below, the load balancing criteria ofthe load-balancing rules for the different load balancers 126 in someembodiments is the same to ensure uniform treatment of the webserver VMtraffic. As shown by host 500 b, multiple webserver VMs 505 can executeon the same host 500, with each of these webserver VMs being serviced bya different load balancer 126. In other embodiments, one load balancercan service multiple VMs on the same host (e.g., multiple VMs for thesame tenant on the same host). Also, in some embodiments, multipleapplication server VMs can execute on the same host with each otherand/or with the webserver VMs.

In the examples illustrated in FIGS. 4-5, the load balancers 126 performa destination network address translation (DNAT) that transforms avirtual IP (VIP) address for the application servers to a specificapplication VM's IP address, called a destination IP address or a DIP.In other embodiments, the DNAT operation can translate other networkaddresses, e.g., it can translate the MAC address to effectuate aMAC-redirect. Also, even though the load balancers in FIGS. 4-5distribute webserver traffic among the application servers of anapplication server group (cluster), the load balancers can be used todistribute traffic from any set of one or more service or compute nodesamong the service or compute nodes of any service/compute node cluster.

FIG. 4 illustrates a load-balancing (LB) rule storage 140 that storesseveral LB rules, with each LB rule associated with one load-balancedcompute or service cluster. Each load-balance rule includes (1) a ruleidentifier 405, (2) several IP addresses 410 of several nodes of theload-balanced node group, and (3) a weight value 415 for each IPaddress. Each rule identifier 405 specifies one or more data tuples thatcan be used to identify a rule that matches a data message flow.

In some embodiments, a rule identifier can include a VIP address (suchas the VIP address of the application server group in FIG. 5) of therule's associated DCN group. As shown, the rule identifier can includein some embodiments any L2-L4 parameters (e.g., source IP address,source port, destination port, protocol, etc.). Also, as shown, the ruleidentifier for a LB rule can include contextual attributes, such asAppID, application name, application version, user ID, group ID, threatlevel, resource consumption, etc. In some embodiments, a load balancersearches a LB data storage by comparing one or more message attributes(e.g., five-tuple header values, contextual attributes) with the ruleidentifiers 405 to identify the highest priority rule with a matchingrule identifier.

Each LB rule's IP addresses 410 are the IP addresses of the compute orservice node that are members of the load-balanced compute or servicegroup that is associated with the rule (e.g., of the load-balanced groupthat is associated with a VIP address specified in the rule's identifier405). As further described below, the addresses of these nodes aresupplied in some embodiments by a controller set that configures theload balancers. In some embodiments, the load balancer translates thedestination IP address of a received data message to one of the IPaddresses 410 (e.g., translates a VIP contained in the data message to aDIP).

In some embodiments, a load balancer performs its load-balancingoperation based on one or more load-balancing criteria. The LB rules ofsome embodiments contain such LB criteria, in order to specify withineach rule how the load balancer should spread the traffic across thenodes of a load-balanced group when a message flow matches that rule. Inthe example illustrated in FIG. 4, the load-balancing criteria is aweighted round robin scheme that is defined by the weight values 415 ofeach rule. Specifically, the weight values 415 for each IP address ofeach LB rule provides the criteria for a load balancer to spread thetraffic to the nodes of a LB node group.

For instance, the application server group of FIG. 5 has fiveapplication servers. Assume that the load-balancing rule fordistributing the webserver traffic amongst these five applicationservers specifies the weight values of 1, 3, 1, 3, and 2 for the five IPaddresses of the five application servers. Based on these values, a loadbalancer would distribute data messages that are part of ten new flowsin the following order: first flow to the first IP address, second tofourth flow to the second IP address, fifth flow to the third IPaddress, sixth to eighth flow to the fourth IP address, and ninth andtenth flow to the fifth IP address. According to this scheme, theassignment of the next batch of new flows loops back through these IPaddresses (e.g., the eleventh flow would be assigned to the first IPaddress and so on).

In some embodiments, the weight values for an LB rule are generated andadjusted by the controller set based on the LB statistics that the loadbalancers (1) collect regarding the data message flows that theydistribute amongst the nodes of the LB node group(s) and (2) provide tocontroller set. Also, to gracefully switch between differentload-balancing criteria, the LB rules in some embodiments specify timeperiods for different load-balancing criteria of a LB rule that arevalid for different periods of time. Accordingly, in some embodiments, aload-balancing rule might specify multiple different sets of destinationnetwork addresses with different temporal values that specify when eachset of addresses is valid. Each of these sets in some embodiments caninclude its own set of LB criteria (e.g., its own set of weight values).

FIG. 6 illustrates a process 600 that the load balancer 126 performs insome embodiments. As shown, the process 600 starts when the loadbalancer receives (at 605) a data message from its corresponding SFEport 260. This port relays this message when it receives the datamessage from its VM or for its VM. In some embodiments, the port relaysthe data message by passing to the load balancer a reference (e.g., ahandle that identifies a location in memory that stores the datamessage) to the data message or the data message's header values.

The process determines (at 610) whether the connection state cache 225stores a record that identifies the destination to which the datamessage should be forwarded. As mentioned above, each time a loadbalancer uses a LB rule to direct a new data message flow to a node of aload-balanced node group, the load balancer in some embodiments createsa record in the connection state cache 225 to store the physical IPaddress of the selected node, so that when the load balancer receivesanother data message within the same flow (i.e., with the samefive-tuple identifier), it can forward it to the same node that it usedfor previous data messages in the same flow. The use of the connectionstate cache 225 allows the load balancer 126 to process the data messageflows more quickly. In some embodiments, each cached record in theconnection state cache 225 has a record identifier that is defined interms of data message identifiers (e.g., five-tuple identifiers). Inthese embodiments, the process compares the received data message'sidentifier (e.g., five-tuple identifier) with the record identifiers ofthe cached records to identify any record with a record identifier thatmatches the received data message's identifier.

When the process 600 identifies (at 610) a record for the received datamessage's flow in the connection state cache 225, the process (at 615)then replaces the message's destination address (e.g., the VIP address)with the destination address (e.g., the DIP) that is stored in therecord in the connection state cache 225. At 615, the process sends theaddress-translated data message along its datapath. In some embodiments,this operation entails returning a communication to the SFE port 260(that called the load balancer to initiate the process 600) to indicatethat the load balancer is done with its processing of the VM datamessage. The SFE port 260 can then handoff the data message to the SFE,or can call another service engine in the I/O chain operator to performanother service operation on the data message. At 615, the process 600also updates in some embodiments the statistics that it maintainsregarding its data message flow processing. After 615, the process 600ends.

When the process 600 determines (at 610) that the connection state cache225 does not store a record for the received data message's flow, theprocess 600 identifies (at 620) one or more contextual attributes forthis data message flow. As mentioned above, the service engines ofdifferent embodiments perform this operation differently. For instance,in some embodiments, the load balancer 126 checks the attribute-mappingstorage 223 for a record that has a record identifier that matches thereceived data message's header values (e.g., its five-tuple identifier).It then uses (at 620) the contextual attribute set of this matchingrecord as the contextual attribute set of the received data messageflow.

In other embodiments, the load balancer 126 queries the context engineto obtain the contextual attribute set for the received data message.With this query, the load balancer supplies the received message's flowidentifier (e.g., five-tuple identifier) or its associated servicetoken. The context engine then uses the message's flow identifier or itsassociated service token to identify a set of contextual attributes inits context attribute storage 145, and it then provides the identifiedset of contextual attributes to the load balancer 126, as explainedabove.

Once the process 600 has obtained the contextual attribute set for thereceived data message, it uses this attribute set along with themessage's other identifiers to identify (at 625) an LB rule in the LBrule storage 140 for the data message received at 605. For instance, insome embodiments, the LB rules have rule identifiers 405 that aredefined in terms of one or more of the five-tuple attributes along withone or more contextual attributes, such as application name, applicationversion, user ID, group ID, AppID, threat level, resource consumptionlevel, etc. To identify the LB rule in the LB rule storage 140, theprocess in some embodiments compares the contextual attributes and/orother attributes (e.g., five-tuple identifier) of the received datamessage with the rule identifiers (e.g., rule identifiers 405) of the LBrules to identify the highest priority rule that has an identifier thatmatches the message's attribute set.

In some embodiments, the process uses different message-attribute setsto perform this comparison operation. For instance, in some embodiments,the message attribute set includes the destination IP address of themessage (e.g., the VIP of the addressed node group) along with one ormore contextual attributes. In other embodiments, the message attributeset includes other attributes, such as one or more of the otherfive-tuple identifiers (e.g., one or more of the source IP, source port,destination port, and protocol). In some embodiments, the messageattribute set includes logical network identifiers such as virtualnetwork identifier (VNI), virtual distributed router identifier (VDRI),a logical MAC address, a logical IP address, etc.

As mentioned above, each LB rule in some embodiments includes two ormore destination addresses (e.g., IP addresses 410), which are thedestination addresses (e.g., IP addresses) of the nodes that are membersof the load-balanced node group. When the process identifies an LB rule(at 630), it selects one of the destination addresses (e.g., IPaddresses) of the rule to replace the virtual address (e.g., the VIPaddress) in the message. Also, as mentioned above, each LB rule in someembodiments stores a set of load-balancing criteria for facilitating theprocess' selection of one of the destination addresses of the LB rule toreplace the message's virtual destination identifier. In someembodiments, the stored criteria are the weight and/or times values thatwere described above by reference to FIGS. 4 and 5. Accordingly, in someembodiments, the process 600 selects one of the matching rule'sdestination addresses based on the selection criteria stored in therule, and changes the message's destination address to the selecteddestination address.

After changing the destination address of the data message, the process(at 630) sends the data message along its datapath. Again, in someembodiments, this operation entails returning a communication to the SFEport 260 (that called the load balancer to initiate the process 600) toindicate that the load balancer is done with its processing of the VMdata message. The SFE port 260 can then handoff the data message to theSFE or the VM, or can call another service engine in the I/O chainoperator to perform another service operation on the data message.

After 630, the process transitions to 635, where in the connection statecache storage 225, it creates a record to identify the compute orservice node in the load-balanced group (i.e., to identify the nodedestination identifier) to use to forward data messages that are part ofthe same flow as the data message received at 605. At 635, the process600 also updates the statistics that it maintains for the node to whichthe message was addressed by the process 600. This update reflects thetransmission of a new data message to this node. After 635, the processends.

Because of its use of contextual attributes to define the ruleidentifiers of the LB rules, the context-based load balancer 126 candistribute the data message flows based on any number of contextualattributes. As mentioned above, examples of such load-balancingoperations include: (1) distributing data message flows associated withthe Finance department on all load-balancing pools, (2) redirecting allthe Finance department's traffic to another pool when the primary poolfor this department is down to make this department's traffic highlyavailable, (3) making all traffic associated with the Doctor's usergroup highly available, and (4) distributing data message flows forFinance applications amongst the service nodes of a low-latency servicenode group. In some embodiments, the load-balancing rules can also bedefined in terms of collected resource consumption, in order todistribute traffic to provide more or less resources to applicationsthat consume a lot of resources on the DCNs.

In some embodiments, the management plane obtains an inventory of allprocesses and services that are running on the VMs on the hosts in adatacenter. The discovery engine 120 of a host 200 in some embodimentsassists in collecting this data from the VMs executing on its host. Insome embodiments, the inventoried process/services are referred to asthe inventoried applications, which include all client processes,services or daemons that utilize network input/output and all serverprocesses that have registered to listen to (i.e., to obtain messages)certain network connections. The discovery engine collects this datausing the GI agents 250 and the MUX 227 in some embodiments.

Based on the data collected by all the discovery engines on all thehosts, the management servers (e.g., the network managers and/or computemanagers) build the inventory of the running applications. In someembodiments, each application is identified by comparing its file hashobtained from the VMs 205 with hashes of application files stored in theapplication data storage of the management plane. The management planein some embodiments has the discovery engines update their datacollection so that the management plane can refresh its inventory on ascheduled basis.

The management plane in some embodiments then provides a rule creationinterface for allowing administrators to create context-based LB rulesand/or policies for the LB engines 126 (as well as service rules for theother service engines 130). The rule creation interface allows theadministrators to define high-level LB policies (and other servicepolicies) based on applications inventoried through the data collectedby the discovery engines 120, and contextual attributes collected by thecontext engines 110 and by the management plane's interface with othermanagement server clusters.

Once the high-level LB policies (and other service policies) are definedin the management plane, the management plane directly supplies some orall of these policies to the management proxies (not shown) on the hosts200, and/or indirectly supplies some or all of these policies to theseproxies through a set of controllers (e.g., network controllers). Insome embodiments, the management proxies publish the received policiesas rules to the context-based service rule storages 140. In someembodiments, the proxies transform these policies before publishing themto the context-based service rule storages 140. For instance, in someembodiments, the policies are published with AppliedTo tuples thatidentify the service nodes and/or logical networks to which they areassociated. In some of these embodiments, the management proxies on thehosts remove the AppliedTo tuple from each service policy, beforepushing the policy as a service rule to the service rule storage 140.Also, as mentioned above, the context engines 110 on the hosts 200 insome embodiments resolve the policies based on collected contextualattributes, in order to generate rules for the service engines.

The firewall engine 128 is a context-based firewall engine that performsits firewall operations based on firewall rules that can be specified interms of not only L2-L4 parameters, but also in terms of contextualattributes. FIG. 7 illustrates several examples of such firewall rules.This figure illustrates a firewall rule data store 140 of someembodiments. As shown, each firewall rule includes a rule identifier 705and a firewall action parameter 710.

In some embodiments, a firewall action parameter 710 can specify any oneof the traditional firewall actions, such as Allow, Drop, Re-Route, etc.Each rule identifier 705 specifies one or more data tuples that can beused to identify a rule that matches a data message flow. As shown, arule identifier can include in some embodiments any L2-L4 parameters(e.g., source IP address, source port, destination port, protocol,etc.). One or more of these parameters can be virtual parameters (e.g.,a VIP of a destination cluster) or a logical identifier (e.g., a logicalnetwork identifier).

In some embodiments, a rule identifier can also include contextualattributes, such as AppID, application name, application version, userID, group ID, threat level, and resource consumption. In someembodiments, a firewall engine searches a firewall data storage bycomparing one or more message attributes (e.g., five-tuple headervalues, contextual attributes) with the rule identifiers 705 to identifythe highest priority rule with a matching rule identifier.

In some embodiments, different firewall engines 128 on different hostsenforce the same set of firewall rules. For instance, in someembodiments, different firewall engines 128 process the same firewallrules on different hosts for VMs of one logical network in order toprovide a level of security on data messages that are transmitted by orreceived for these VMs. For this logical network, these firewall engines128 collectively form a distributed firewall engine (i.e., a single,conceptual logical firewall engine) that spans across the multiplehosts.

FIG. 8 illustrates several more detailed examples of the context-basedfirewall rules of some embodiments. In these examples, the ruleidentifier 705 of each rule is expressed in terms of the five-tupleidentifier and one or more contextual attributes. Each rule has one ormore attributes in its five-tuple identifier that are wildcard valuesdesignated by an asterisk in order to specify that the value of theseattributes do not matter (i.e., the data message flow can have any valuefor these attributes without failing to match the rule).

The first rule 835 specifies that all data message flows from Skypeversion 1024 should be dropped. The rule identifier for this rule isexpressed only in terms of the contextual attributes of the data messageflow. As mentioned above, and further described below, each time thefirewall engine 128 identifies a new data message flow, it identifiesthe flow's contextual attributes by interacting with the context engineor by examining the records in its attribute-mapping storage 223 toidentify a record that specifies the contextual attributes for theflow's five-tuple identifier.

The second rule 830 specifies that all data message flows that have aGroup ID equal to Nurses and AppID equal to YouTube traffic are to bedropped. By enforcing this rule, the firewall engine 128 can make surethat nurses that login to its VM 205 cannot view YouTube traffic. Again,the rule identifier for this rule is expressed only in terms of thecontextual attributes of the data message flow. In this example, thecontextual attributes are the Group ID and the AppID.

FIG. 9 presents an example that illustrates the enforcement of thesecond rule 830 by the firewall engine 128. Specifically, it shows thisfirewall engine 128 allowing a first data message 905 from a browser 910to pass through, while blocking a second data message 915 from thisbrowser. As shown, both these data messages are associated with anoperation that a nurse 920 has performed on the browser. The first datamessage flow is allowed to pass through as it relates to an email thatthe nurse is sending through the browser. This firewall engine 128allows this message to go through because it does not match any firewallrule that requires the message to be blocked. The firewall engine 128,on the other hand, blocks the second data message as it relates to thenurse trying to watch a YouTube video, and this type of data messageflow is prohibited by rule 830.

The third rule 825 in FIG. 8 specifies that all data message flows thatare associated with a high threat level indicator should be blocked ifthey are going to a particular destination IP address A. The ruleidentifier for this rule is defined in terms of a contextual attribute(i.e., the high threat level indicator) and one attribute (thedestination IP address) in the five-tuple identifier of the datamessage.

FIG. 10 presents an example that in two stages illustrates theenforcement of this rule 825 by the firewall engine 128. Specifically,it shows in a first stage 1002 the firewall engine 128 allows datamessages 1010 to pass from a VM 205 to another VM 1020 (outside of thehost) that has the particular destination IP address A. In the secondstage 1004, an application 1005 is installed on the VM 205. Thisapplication is designated as a high threat application by the threatdetector 132. Whenever a new data message flow starts on the VM, thecontext engine associates this data message flow with a high threatlevel tag. Accordingly, in the second stage 1004, the firewall engine128 blocks a data message 1050 from the VM 205 to the other VM 1020 asthis data message is associated with the high threat level, and the rule815 prohibits such a data message to be sent to IP address A of the VM1020.

The fourth and fifth rules 820 and 815 in FIG. 8 specify that datamessages associated with the Doctor and Nurses groups can access VMsassociated with a VIP address A, while data messages associated with theAccountant group cannot access these VMs. The rule identifier for thefourth rule is defined in terms of two contextual attributes (i.e.,Doctor and Nurse group identifiers) and one attribute (the VIPdestination address A) in the five-tuple identifier of the data message.The rule identifier for the fifth rule is defined in terms of onecontextual attribute (i.e., Accountant group identifier) and oneattribute (the VIP destination address A) in the five-tuple identifierof the data message. In some embodiments, the VIP address is an addressof a cluster of VMs that perform the same function, and a load balancerwill translate this VIP address to the IP address of one of the VMs inthe cluster.

FIG. 11 presents an example that illustrates the enforcement of thefourth and fifth rules 820 and 815 by the firewall engine 128.Specifically, it shows two users concurrently logged into one VM that isacting as a terminal server. One of these users is a Nurse X, whileanother user is an accountant Y. FIG. 11 further shows that the firewallengine 128 allows a first data message 1105 from the Nurse X's sessionto pass through to a VM in a VM cluster 1150 identified by thedestination IP address VIP A. It also shows the firewall engine blockinga second data message 1110 from the Accountant Y's session from reachingany of the VMs in this VM cluster, because the fifth rule 815 preventsdata messages that are associated with the Accountants Group ID to reachthe destination IP address VIP A.

In FIG. 11, the two data messages are for two different actual users whoare concurrently logged into a VM. In other cases, only one user mightbe actually logged onto a VM, but administrative processes might berunning on the VM in conjunction with the processes that run for theapplications started by the logged in user. The administrative processescan be services/daemons running in a VM in a different user context thanthe logged in user. Services generally run in admin/root context and notin the logged in user context. This is a potential security hole as itmight allow any application running in a non-logged on user context toaccess a network resource. Accordingly, even when only a single user islogged into a VM, it can be desirable to specify firewall rules thattreat differently the data messages associated with backgroundadministrative processes from data messages associated with processesthat run for the applications started by the logged in user.

As an example, the sixth rule 810 allows data messages of processesassociated with the applications operated by an individual in the HighSecurity Group to access other VMs with sensitive data (in this example,these VMs are part of a cluster of VMs associated with an IP address VIPB), while the seventh rule 805 blocks data messages associated withbackground administrative processes from accessing such VMs. This isuseful for ensuring that IT personnel or hackers cannot create a backdoor to access sensitive data by installing administrative processesthat access high security VMs that piggyback off the login session of auser with the appropriate clearance.

FIG. 12 presents an example that illustrates the enforcement of thesixth and seventh rules 810 and 805 by the firewall engine 128.Specifically, it shows two data message flows concurrently emanatingfrom one VM. One data message flow is associated with the CEO, whileanother is associated with a background IT utility process calledUtility Q. FIG. 12 further shows that the firewall engine 128 allows adata message 1205 from the CEO's session to pass through to a VM in ahigh security cluster 1250 identified by the VIP address B. It alsoshows the firewall engine blocking a second data message 1210 from theUtility Q's session from reaching any of the VMs in the high securitycluster, because the seventh rule 805 prevents data messages that areassociated with administrative processes (such as the Utility Q process)from reaching the VIP address B.

The firewall engine can differentiate the data message flows for twodifferent processes that run concurrently on a VM for two differentlogin/administrative credentials because the context engine collects theuser and group identifiers for each data message flow when each flowstarts, and associates each flow with its user and group identifiers.FIG. 13 illustrates a process 1300 that the context engine performs tocollect the user and group identifiers each time it receives a newnetwork connection event from a GI agent.

The process 1300 initially receives (at 1305) a notification of a newnetwork connection event from a GI agent 250 on a VM 205. As mentionedabove, the GI agent in some embodiments provides the followinginformation in a new network connection notification: the connection'sfive-tuple identifier, the identifier of the process requesting thenetwork connection, a user identifier associated with the requestingprocess, and a group identifier associated with the requesting process.

Next, at 1310, the process 1300 queries the GI agent to collect anyother contextual attributes needed for the new network connection event.Examples of such additional parameters include additional parametersassociated with the process requesting the network connection. At 1315,the process 1300 then publishes one or more context attribute records toone or more service engines. In some embodiments, each context attributerecord to each service engine includes the connection's five-tupleidentifier and a set of one or more context attributes, including theuser identifier and/or the group identifier. The service engines thenstore the provided contextual attribute records in theirattribute-mapping storages 223, so that they can use these records toidentify the context attribute sets associated with different datamessage flows that they process. For service engines that have differentservice rules for different processes concurrently running on a VM fordifferent user accounts, the context attribute sets include a useridentifier or a group identifier to allow these service engines toassociate different data message flows from the VM to differentuser/group identifiers.

In some embodiments, the context engine does not include in a serviceengine's context attribute record the contextual attributes that are notneeded by the service engine. Also, in some embodiments, the contextengine provides different context attribute records to different contextengines for the same network connection event, because different serviceengines need different sets of context attributes. As described above,the context engine 110 in some embodiments does not push the contextattribute sets for new network connections to some or all of the serviceengines, but rather has these service engines pull these attribute sets.

In some embodiments, the context engine can associate a data messageflow on a source host with the source VM (i.e., the VM that is thesource of the data message flow) with a contextual attribute of adestination VM on the same host or a different destination host. Thefirewall engine 128 in these embodiments can then use suchdestination-based contextual attributes to resolve firewall rules. Forinstance, the firewall engine can drop all data messages addressed to aparticular type of server (e.g., a Sharepoint server). To support suchdestination-based rules, the context engines of some embodiments directsthe GI agents to identify the processes that register for notificationson particular ports, and uses this information along with processidentifiers and hashes to identify the applications that serve asdestinations of data message flows. The information collected by thecontext engines on the different hosts are collected by the managementplane (e.g., by management servers that operate on separate computers oron the same hosts that execute the VMs), which aggregates this data anddistributes the aggregated data to the other context engines. Thedistributed information can then be used by the context engines on thehost to resolve contextual policies on these hosts, in order to supplycontext-based rules to the context-based service engines on these hosts.

FIG. 14 illustrates a process 1400 that the firewall engine 128 performsin some embodiments. As shown, the process 1400 starts when the firewallengine receives (at 1405) a data message from its corresponding SFE port260. This port relays this message when it receives the data messagefrom its VM or for its VM. In some embodiments, the port relays the datamessage by passing to the firewall engine a reference (e.g., a handlethat identifies a location in memory that stores the data message) tothe data message or the data message's header values.

The process determines (at 1410) whether the connection state cache 225stores a record that identifies a firewall action for the message flowof the received data message. As mentioned above, each time a firewallengine uses a firewall rule to process a new data message, the firewallengine in some embodiments creates a record in the connection statecache 225 to store the firewall action performed, so that when thefirewall engine receives another data message within the same flow(i.e., with the same five-tuple identifier), it can perform the samefirewall action that it performed on previous data messages in the sameflow. The use of the connection state cache 225 allows the firewallengine 128 to process the data message flows more quickly. In someembodiments, each cached record in the connection state cache 225 has arecord identifier that is defined in terms of data message identifiers(e.g., five-tuple identifiers). In these embodiments, the processcompares the received data message's identifier (e.g., five-tupleidentifier) with the record identifiers of the cached records toidentify any record with a record identifier that matches the receiveddata message's identifier.

When the process 1400 identifies (at 1410) a record for the receiveddata message's flow in the connection state cache 225, the process (at1415) then performs the firewall action (e.g., Allow, Drop, Re-Route,etc.) specified in this record. Assuming that the firewall action doesnot require the data message to be dropped, the process 1400 sends theprocessed data message along its datapath. In some embodiments, thisoperation entails returning a communication to the SFE port 260 (thatcalled the firewall engine to initiate the process 1400) to indicatethat the firewall engine is done with its processing of the VM datamessage. The SFE port 260 can then handoff the data message to the SFEor the VM, or can call another service engine in the I/O chain operatorto perform another service operation on the data message.

When the firewall action performed at 1415 results in the dropping ofthe data message, the process 1400 notifies (at 1415) the SFE port 260of this operation. Also, when the firewall action performed at 1415requires the data message to be re-routed, the process 1400 performs (at1415) a network address translation on the data message in order toeffectuate this re-routing, and then returns (at 1415) the data messageto the SFE port so that the data message can be sent along its datapath.After 1415, the process 1400 ends.

When the process 1400 determines (at 1410) that the connection statecache 225 does not store a record for the received data message's flow,the process 1400 identifies (at 1420) one or more contextual attributesfor this data message flow. As mentioned above, the service engines ofdifferent embodiments perform this operation differently. For instance,in some embodiments, the firewall engine 128 checks theattribute-mapping storage 223 for a record that has a record identifierthat matches the received data message's header values (e.g., itsfive-tuple identifier). It then uses (at 1420) the contextual attributeset of this matching record as the contextual attribute set of thereceived data message flow.

In other embodiments, the firewall engine 128 queries the context engineto obtain the contextual attribute set for the received data message.With this query, the firewall engine supplies the received message'sflow identifier (e.g., five-tuple identifier) or its associated servicetoken. The context engine then uses the message's flow identifier or itsassociated service token to identify a set of contextual attributes inits context attribute storage 145, as explained above.

Once the process 1400 has obtained the contextual attribute set for thereceived data message, it uses this attribute set along with themessage's other identifiers to identify (at 1425) a firewall rule in thefirewall rule data store 140 for the data message received at 1405. Forinstance, in some embodiments, the firewall rules have rule identifiers705 that are defined in terms of one or more of the five-tupleattributes along with one or more contextual attributes, such asapplication name, application version, user ID, group ID, AppID, threatlevel, resource consumption level, etc. To identify the firewall rule inthe firewall rule data store 140, the process in some embodimentscompares the contextual attributes and/or other attributes (e.g.,five-tuple identifier) of the received data message with the ruleidentifiers (e.g., rule identifiers 705) of the firewall rules toidentify the highest priority rule that has an identifier that matchesthe message's attribute set.

In some embodiments, the process uses different message-attribute setsto perform this comparison operation. For instance, in some embodiments,the message attribute set includes one or more of the other five-tupleidentifiers (e.g., one or more of the source IP, source port,destination port, and protocol) along with one or more contextualattributes. In some embodiments, the message attribute set includeslogical network identifiers such as virtual network identifier (VNI),virtual distributed router identifier (VDRI), a logical MAC address, alogical IP address, etc.

After the process identifies a firewall rule (at 1425), it performs (at1430) the firewall action (e.g., Allow, Drop, Re-Route, etc.) of thisrule on the received data message. Assuming that the firewall actiondoes not require the data message to be dropped, the process 1400 sends(at 1430) the processed data message along its datapath. In someembodiments, this operation entails returning a communication to the SFEport 260 (that called the firewall engine to initiate the process 1400)to indicate that the firewall engine is done with its processing of theVM data message. The SFE port 260 can then handoff the data message tothe SFE or the VM, or can call another service engine in the I/O chainoperator to perform another service operation on the data message.

When the firewall action performed at 1430 results in the dropping ofthe data message, the process 1400 notifies (at 1430) the SFE port 260of this operation. Also, when the firewall action performed at 1430requires the data message to be re-routed, the process 1400 performs (at1430) a network address translation on the data message in order toeffectuate this re-routing, and then returns (at 1430) the data messageto the SFE port so that the data message can be sent along its datapath.

After performing the firewall action at 1430, the process creates (at1435) a record in the connection state cache storage 225. This recordidentifies the firewall action for the received data message's flow. Insome embodiments, this record has a record identifier that is defined byreference to the data message flow's identifier (e.g., its five tupleidentifier). After 1435, the process ends.

As mentioned above, the management servers in some embodiments interactwith the discovery engines 120 executing on the hosts 200 in a datacenter to obtain and refresh inventory of all processes and servicesthat are running on the VMs on the hosts. In some embodiments, themanagement servers (also referred to above and below as the managementplane) then provides a rule creation interface for allowingadministrators to create context-based firewall rules and/or policiesfor the firewall engines 128 (as well as service rules for the otherservice engines 130). The rule creation interface allows theadministrators to define high-level firewall policies (and other servicepolicies) based on applications inventoried through the data collectedby the discovery engines 120, and contextual attributes collected by thecontext engines 110 and by the management plane's interface with othermanagement server clusters.

Once the high-level firewall policies (and other service policies) aredefined in the management plane, the management plane directly suppliessome or all of these policies to the management proxies (not shown) onthe hosts 200, and/or indirectly supplies some or all of these policiesto these proxies through a set of controllers (e.g., networkcontrollers). In some embodiments, the management proxies publish thereceived policies as rules to the context-based service rule storages140. In some embodiments, the proxies transform these policies beforepublishing them to the context-based service rule storages 140. Forinstance, in some embodiments, the policies are published with AppliedTotuples that identify the service nodes and/or logical networks to whichthey are associated. In some of these embodiments, the managementproxies on the hosts remove the AppliedTo tuple from each servicepolicy, before pushing the policy as a service rule to the service rulestorage 140. Also, as mentioned above, the context engines 110 on thehosts 200 in some embodiments resolve the policies based on collectedcontextual attributes, in order to generate rules for the serviceengines.

The encryption engine 124 is a context-based encryptor that performs itsencryption/decryption operations based on encryption rules that can bespecified in terms of not only L2-L4 parameters, but also in terms ofcontextual attributes. FIG. 15 illustrates an example of suchcontext-based encryption rules. These rules are used independently bydifferent encryption engines 124 on different hosts 200 toencrypt/decrypt data messages sent by and received for the VMs 205 onthese hosts. In this manner, the encryption engines 124 that enforce thesame encryption rules on the different hosts (e.g., for one tenant orone logical network) collectively form a distributed encryption engine(i.e., a single, conceptual logical encryption engine) that spans acrossthe multiple hosts to uniformly perform a desired set of encryption anddecryption operations. In some embodiments, each VM 205 has its ownencryption engine, while in other embodiments, one encryption engine 124can service multiple VMs 205 on the same host (e.g., multiple VMs forthe same tenant on the same host).

FIG. 15 illustrates an encryption rule data store 140 that storesseveral encryption rules. Each encryption rule includes (1) a ruleidentifier 1505, (2) an encryption type identifier 1510, and (3) a keyidentifier 1515. Each rule identifier 1505 specifies one or more datatuples that can be used to identify a rule that matches a data messageflow. In some embodiments, a rule identifier can include any L2-L4parameters (e.g., source IP address, source port, destination port,destination IP, protocol, etc.). These L2-L4 parameters in someembodiments can be defined in the physical domain or logical domain.Also, as shown, the rule identifier can include contextual attributes,such as AppID, application name, application version, user ID, group ID,threat level, and resource consumption.

In some embodiments, an encryptor 124 searches an encryption rule datastore 140 by comparing one or more message attributes (e.g., five-tupleheader values, contextual attributes) with the rule identifiers 1505 toidentify the highest priority rule with a matching rule identifier.Also, in some embodiments, the encryption rule data store 140 has adefault rule that is used when no other rule matches a data messageflow. In some embodiments, the default rule specifies no encryption keyas no rule exists for encrypting the data message flow. Also, in someembodiments, when the default rule is returned to the encryptor 124, theencryptor 124 does not encrypt the data message flow for which it isperforming the check.

The encryption type 1510 of each encryption rule specifies the type ofencryption/decryption to use, while the key identifier 1515 of each ruleidentifies the key to use for the encryption/decryption. In someembodiments, the encryption rules only specify the key identifiers 1515and do not specify the encryption types 1510, because the keyidentifiers identify both the key and the type of encryption/decryptionor these types are otherwise specified (e.g., preconfigured) in theencryptor.

The encryption and decryption operations of the encryption engine 124will now be described by reference to FIGS. 16-18. In some embodiments,the encryption and decryption operations use the same key or transposedversions of the same key, because these embodiments use a symmetricencryption scheme in which the same key is used to encrypt and decryptthe message, or transposed versions of the same key are used to encryptand decrypt the message. Other embodiments use asymmetric encryptionschemes (e.g., source encryptor using its private key, and thedestination encryptor using the public key of the source encryptor).

FIG. 16 illustrates a process 1600 that the encryptor 124 performs toencrypt a data message sent by a VM 205 on the host 200. As shown, theprocess 1600 starts when the encryptor 124 receives (at 1605) a datamessage from its corresponding SFE port 260. This port relays thismessage when it receives the data message from its VM. In someembodiments, the port relays the data message by passing to theencryptor a reference (e.g., a handle that identifies a location inmemory that stores the data message) to the data message or the datamessage's header values.

Next, at 1610, the encryptor determines whether its connection statecache 225 stores a cached encryption record for the received datamessage. In some embodiments, each time an encryptor finds an encryptionrule for a VM data message in some embodiments, it creates a cachedencryption record that stores the encryption rule, a reference to theencryption rule, the encryption key, and/or the encryption key'sidentifier in the connection state cache 225.

The encryptor creates this cache record so that when it receives anotherdata message for the same data message flow, the encryptor does not haveto search the encryption rule data store 140 to identify an encryptionrule for the subsequently received data messages in the same flow. Insome embodiments, each cached record in the connection state cache 225has a record identifier that is defined in terms of data messageidentifiers (e.g., five-tuple identifiers). In these embodiments, theprocess 1600 compares the received data message's identifier (e.g.,five-tuple identifier) with the record identifiers of the cached recordsto identify any record with a record identifier that matches thereceived data message's identifier.

When the process 1600 identifies (at 1610) a cached encryption recordfor the received data message in the connection state cache 225, theprocess (at 1615) then uses the key identified by the identifiedencryption records to encrypt the received data message. In theembodiments where the cached record contains the encryption rule or areference to the encryption rule, the process 1600 retrieves a keyidentifier from the stored or referenced rule and uses this identifierto retrieve a key from a key data store that is stored on the host 200or from a key manager on the host or operating outside of the host.Similarly, in the embodiments where the cached record contains the keyidentifier, the process 1600 retrieves a key identifier from the cachedrecord and uses this identifier to retrieve a key from the local orremote key data store or key manager.

In some embodiments, the process encrypts (at 1615) the data message'spayload (e.g., the L2 payload) by using the identified encryption key,while generating an integrity check value (ICV) hash of the payload andsome or all of the header values (e.g., the physical L3 and L4 headervalues and/or logical L2 or L3 header values), so that the message'sdestination would have (1) to decrypt the encrypted portion of the datamessage, and (2) to verify the authenticity and integrity of the payloadand header values that were used for the ICV calculation.

For some or all of the data messages, the encryption process 1600 insome embodiments also encrypts (at 1615) a portion of the data messageheader. For data messages that are exchanged between machines associatedwith a logical network, some embodiments encrypt all of the physicalheader values of the data message. Some of these embodiments perform ICVoperation on the logical network identifier (e.g., the VNI) and thepayload so that the decryptor at the destination host can verify theauthenticity and integrity of the encrypted data message.

After encrypting the data message, the process (at 1615) sends theencrypted data message along its datapath. In some embodiments, thisoperation entails returning a communication to the SFE port 260 (thatcalled the encryptor to initiate the process 1600) to let the port knowthat the encryptor is done with its processing of the data message. TheSFE port 260 can then handoff the data message to the SFE 210 or cancall another I/O chain operator to perform another operation on the datamessage. After 1615, the process 1600 ends.

When the process 1600 determines (at 1610) that the connection statecache 225 does not store any cached record that matches the receiveddata message, the process 1600 identifies (at 1620) one or morecontextual attributes for this data message flow. As mentioned above,the service engines of different embodiments perform this operationdifferently. For instance, in some embodiments, the encryption engine124 checks the attribute-mapping storage 223 for a record that has arecord identifier that matches the received data message's header values(e.g., its five-tuple identifier). It then uses (at 1620) the contextualattribute set of this matching record as the contextual attribute set ofthe received data message flow.

In other embodiments, the encryption engine 124 queries the contextengine 110 to obtain the contextual attribute set for the received datamessage. With this query, the encryption engine supplies the receivedmessage's flow identifier (e.g., five-tuple identifier) or itsassociated service token, which the context engine then uses to identifya set of contextual attributes in its context attribute storage 145, asexplained above.

Once the process 600 has obtained the contextual attribute set for thereceived data message, it uses this attribute set by itself or alongwith the message's other identifiers (e.g., five-tuple identifiers) toidentify (at 1625) an encryption rule in the encryption rule data store140 that matches the received data message's attributes. For instance,in some embodiments, the encryption rules have rule identifiers that aredefined in terms of one or more of non-contextual attributes (e.g.,five-tuple attributes, logical attributes, etc.) and/or one or morecontextual attributes, such as application name, application version,user ID, group ID, AppID, threat level, resource consumption level, etc.To identify the encryption rule in the encryption rule data store 140,the process in some embodiments compares contextual attributes and/orother attributes (e.g., five-tuple identifier) of the received datamessage with the rule identifiers (e.g., rule identifiers 1505) of theencryption rules to identify the highest priority rule that has anidentifier that matches the message's attribute set.

After 1625, the process determines (at 1630) whether it identified anencryption rule that specifies that the received data message should beencrypted. As mentioned above, the encryption rule data store 140 has adefault encryption rule that matches all data message, and is returnedwhen no other encryption rule matches a received data message. Thedefault encryption rule in some embodiments specifies that the receiveddata message should not be encrypted (e.g., specifies a default keyidentifier that corresponds to a no-encryption operation).

When the process 1600 determines (at 1630) that the data message shouldnot be encrypted, the process sends (at 1635) the message unencryptedalong the message's datapath. This operation 1630 entails informing itsSFE port 260 that it has completed processing the data message. After1635, the process transitions to 1645, where in the connection statecache storage 225, it creates a record to indicate that no encryptionshould be performed for the received data message flow. In someembodiments, this record is addressed in the connection state cache 225based on the five-tuple identifier of this flow. After 1645, the processends.

When the process determines (at 1630) that the data message should beencrypted, the process then (at 1640) retrieves a key identifier fromthe identified rule, uses this identifier to retrieve a key from a localor remote key data store or manager, as described above, and encryptsthe received data message with the retrieved key. This encryption of thedata message (at 1640) is identical to the encryption operation 1615that was above described. For instance, as described above, the process1600 encrypts the data message's payload (e.g., the L2 payload) by usingthe identified encryption key, while performing ICV operation on thepayload and some or all of the header values (e.g., the physical L3 andL4 header values, logical L2 or L3 header values, and/or the logicalnetwork identifiers, such as VNIs and VDRIs). For some or all of thedata messages, the encryption process 1600 in some embodiments alsoencrypts (at 1640) some or all of the data message's header.

After encrypting the data message, the process sends (at 1635) theencrypted data message along its datapath. Again, in some embodiments,this operation entails returning a communication to the SFE port 260 tolet the port know that the encryptor is done with its processing of thedata message. The SFE port 260 can then handoff the data message to theSFE 210 or can call another I/O chain operator to perform anotheroperation on the data message.

When the encryption rule that is identified at 1630 is a rule that wasdynamically created after dynamically detecting an event, the encryptorhas to make sure (at 1640) that the key identifier for the key that isused to encrypt the data message is included in the data message headerbefore it is sent. The process 1600 accomplishes this goal differentlyin different embodiments. In some embodiments, the process 1600 passes(at 1640) the key identifier to the SFE port 260 (that called it) sothat the port or an I/O chain operator that it calls can insert the keyidentifier in the data message header. For instance, in someembodiments, one service engine (e.g., another I/O chain operator)encapsulates the data message with a tunnel header that is used toestablish an overlay logical network. In some of these embodiments, theSFE port 260 passes the key identifier that it receives from the process1600 to this service engine so that it can include this key identifierin its header.

In other embodiments, the process 1600 does not pass a key identifier tothe SFE port and this port does not have another service engineencapsulate a key identifier in the overlay network's tunnel header. Insome of these embodiments, the SFE port 260 simply has the serviceengine include in the overlay network's tunnel header an indication thatthe data message is encrypted. In these embodiments, a decryptor (e.g.,an encryption engine 124) executing on the host with the destination DCNcan identify the correct key to use to decrypt the data message based onpreconfigured information (e.g., a whitebox solution that allows thedecryptor to pick the correct key based on a prior key specified forcommunicating with the source DCN, or based on header values of the datamessage flow), or based on out-of-band communication with a controlleror a module on the source host regarding the appropriate key to use.

After 1640, the process transitions to 1645, where in the connectionstate cache storage 225, it creates a record to store the encryptionrule identified at 1625, a reference to this encryption rule, the keyidentifier specified in this encryption rule, and/or the retrieved keyspecified by this key identifier. As mentioned above, this cached recordhas a record identifier that in some embodiments includes the receiveddata message's identifier (e.g., five-tuple identifier). After 1645, theprocess ends.

FIG. 17 illustrates a process 1700 that an encryption engine 124performs to decrypt an encrypted data message that an SFE port 260 or265 receives on a destination host that executes the destination VM ofthe data message. This encryption engine is referred to as the decryptorbelow. In some embodiments, the decryptor performs this operation whenits corresponding SFE port calls the decryptor to check whether areceived data message is encrypted, and if so, to decrypt this message.

In some embodiments, the SFE port calls the encryption engine 124 whenthe SFE port determines that the received data message is encrypted. Forinstance, in some embodiments, the data message is sent to thedestination host along a tunnel, and the header for this tunnel has anidentifier that specifies that the data message is encrypted. In someembodiments, the decryptor performs this process only if the headervalue of the received data message does not specify a key identifierthat identifies a key for decrypting the data message. When the headervalue does specify such a key identifier, the decryptor uses adecryption process 1800 of FIG. 18, which will be described below.

Also, in some embodiments, the received data message has a value (e.g.,a bit) that specifies whether the message is encrypted. By analyzingthis value, the decryptor will know whether the message is encrypted.When this value specifies that the message is not encrypted, thedecryptor does not call either the process 1700 or 1800 to decrypt theencrypted message. Instead, the decryptor informs the SFE port that itcan send the data message along its datapath.

As shown, the process 1700 initially identifies (at 1705) a set ofmessage attributes that the process uses to identify an encryption rulethat is applicable to the received data message. In differentembodiments, the message-attribute set that is used to retrieve the rulecan be different. For example, in some embodiments, thismessage-attribute set includes the received data message's five-tupleidentifier. In some embodiments, this message-attribute set alsoincludes the logical network identifier associated with the receiveddata message.

After 1705, the decryptor determines (at 1710) whether its encryptionstate cache 225 stores a cached encryption rule for the messageattribute set identified at 1705. Like an encryptor, each time adecryptor finds an encryption rule for a data message in someembodiments, it stores the encryption rule, a reference to theencryption rule, this rule's key identifier or this rule's key in theconnection state cache 225, so that when it receives another datamessage with the same identified message-attribute set (e.g., when itreceived another data message that is part of the same data flow as theoriginal data message), the decryptor does not have to search theencryption rule data store(s) to identify an encryption rule for thesubsequently received data message. As mentioned above, the connectionstate cache 225, in some embodiments, stores the encryption rules basedon five-tuple identifiers of the data messages. Accordingly, beforesearching the encryption rule data store 140, the decryptor in someembodiments first determines whether the connection state cache 225stores a matching cached record for the received data message.

When the process 1700 identifies (at 1710) matching cached record forthe received data message in the connection state cache 225, the process(at 1715) then uses this record to identify a key, which it then uses todecrypts the encrypted portion of the received data message. In someembodiments, the cached record includes the key, while in otherembodiments, this record includes the key identifier or the rule or areference to the rule, which contains the key identifier. In the latterembodiments, the process uses the key identifier in the cached record orin the stored or referenced rule to retrieve a key from a local orremote key data store or manager, and then decrypts the encryptedportion of the received data message with the retrieved key.

In some embodiments, part of the decryption operation (at 1715) is toauthenticate the ICV generated hash of the data message header andpayload. Specifically, when a portion of the received data message(e.g., its physical (e.g., L3 or L4) header values, or its logical(e.g., VNI) header values) is hashed along with the payload through anICV operation by the encryptor, the decryption operation verifies thisportion to validate the authenticity and integrity of the encrypted datamessage.

After decrypting the data message (at 1715), the process (at 1715) sendsthe decrypted data message along its datapath. In some embodiments, thisoperation entails returning a communication to the SFE port (that calledthe decryptor to initiate the process 1700) to let the port know thatthe decryptor is done with its processing of the data message. The SFEport can then allow the data message to reach the destination VM or cancall another I/O chain operator to perform another operation on the datamessage. After 1715, the process 1700 ends.

When the process 1700 determines (at 1710) that the connection statecache 225 does not store an encryption rule for the attribute setidentified at 1705, the process 1700 searches (at 1720) the encryptionrule data store 140 to identify an encryption rule for the received datamessage. In some embodiments, the destination host receives anout-of-band communication from the source host (directly or through acontroller set) that provides data from which the destination host canidentify a key identifier, or an encryption rule with the keyidentifier, for decrypting the encrypted data message. In some of theseembodiments, the out-of-band communication includes the identifier(e.g., five-tuple identifier) for the data message.

In other embodiments, the encryption engine 124 on the destination hostidentifies the correct key to use to decrypt the data message based onpreconfigured information. For example, in some embodiments, theencryption engines 124 on source and destination hosts use a whiteboxsolution (1) that steps through encryption keys according to apreconfigured scheme, or (2) that selects encryption keys based onattributes (e.g., five-tuple identifiers) of the data messages. Byhaving the source and destination encryption engines follow the samescheme to step through or select the encryption keys, the whiteboxscheme ensures that the encryption engine at the destination host'sencryptor 124 can select the same encryption key for decrypting thereceived data message as the source host's encryptor 124 used to encryptthe data message.

When the process 1700 cannot find an encryption rule that identifies akey, the process 1700 in some embodiments initiates an error handlingprocess to resolve the unavailability of a decryption key for decryptingthe encrypted message. This error handling process in some embodimentsqueries a network agent to determine whether it or the controller setstores an encryption rule for the message attribute set identified at1705. When the agent has such an encryption rule, it provides it to theprocess (at 1720). However, in other embodiments, the error handlingprocess does not contact the network agent to obtain the key. Instead,it just flags this issue for an administrator to resolve.

When that the process identifies (at 1720) a key identifier or anencryption rule with a key identifier, the process (at 1725) uses thekey identifier to retrieve a key from a local or remote key data storeor manager, and decrypts the received data message with the retrievedkey. In some embodiments, part of the decryption operation (at 1725) isto authenticate an ICV generated hash of the data message header andpayload. Specifically, when a portion of the received data message(e.g., its physical (e.g., L3 or L4) header values, or its logical(e.g., VNI) header values) is hashed through an ICV operation along withthe payload by the encryptor, the decryption operation verifies thisportion to validate the authenticity and integrity of the encrypted datamessage.

After decrypting the data message, the process (at 1725) sends thedecrypted data message along its datapath. In some embodiments, thisoperation entails returning a communication to the SFE port (that calledthe decryptor to initiate the process 1700) to let the port know thatthe decryptor is done with its processing of the data message. The SFEport can then allow the data message to reach the destination VM or cancall another I/O chain operator to perform another operation on the datamessage.

After 1725, the process transitions to 1730, where in the connectionstate cache storage 225, it creates a record to specify that decryptionkey, or the identifier to this key, that should be used to decrypt datamessages with message-attribute sets that are similar to the setidentified at 1705 (e.g., to decrypt data messages that are part of thesame flow as the received data message). In some embodiments, thisrecord is addressed in the connection state cache cache 225 based on thefive-tuple identifier of the received data message. After 1730, theprocess ends.

In some embodiments, the header value (e.g., the tunnel header) of thereceived encrypted data message stores a key identifier that identifiesa key for decrypting the data message. The encryption engine 124 on ahost device then performs its decryption operation by using the keyidentified by the key identifier. FIG. 18 illustrates a process 1800that the encryption engine 124 performs to decrypt an encrypted datamessage that includes the key identifier in its header. In someembodiments, a decryptor in the encryption engine 124 performs thisoperation when its corresponding SFE port 260 or 265 calls the decryptorto check whether a received data message is encrypted, and if so, todecrypt this message. In some embodiments, the decryptor performs thisprocess only if the header value of the received data message specifiesa key identifier that identifies a key for decrypting the data message.

As shown, the process 1800 initially extracts (at 1805) the keyidentifier from the received data message. Next, the process uses (at1810) the key identifier to retrieve a key from a local key datastore/manager on the destination host or a remote key data store/managernot on the destination host, and then uses (at 1815) this key to decryptthe received data message. As mentioned above, part of the decryptionoperation (at 1815) is to authenticate the ICV generated hash (of thereceived data message's header and payload) that is encrypted with thepayload of the data message. In some embodiments, the process 1800stores in the cache data store 225 the key so that it does not need toidentify this key for other data messages in the same data message flowas the received data message.

After decrypting the data message, the process sends (at 1820) thedecrypted data message along its datapath. In some embodiments, thisoperation entails returning a communication to the SFE port (that calledthe decryptor to initiate the process 1800) to let the port know thatthe decryptor is done with its processing of the data message. The SFEport can then allow the data message to reach the destination VM or cancall another I/O chain operator to perform another operation on the datamessage. After 1820, the process 1800 ends.

Because of its use of contextual attributes to define the ruleidentifiers of the Encryption rules, the context-based encryptor 124 candistribute the data message flows based on any number of contextualattributes. As mentioned above, examples of such encryption operationsinclude: (1) encrypt all traffic from Outlook (started on any machine)to Exchange Server, (2) encrypt all communication between applicationsin a three tier Webserver, Application Server and Database Server, (3)encrypt all traffic originating from the Administrators Active Directorygroup, etc.

As mentioned above, the management servers in some embodiments interactwith the discovery engines 120 executing on the hosts 200 in a datacenter to obtain and refresh inventory of all processes and servicesthat are running on the VMs on the hosts. The management plane in someembodiments then provides a rule creation interface for allowingadministrators to create context-based encryption rules and/or policiesfor the encryption engines 124 (as well as service rules for the otherservice engines 130). The rule creation interface allows theadministrators to define high-level encryption policies (and otherservice policies) based on applications inventoried through the datacollected by the discovery engines 120, and contextual attributescollected by the context engines 110 and by the management plane'sinterface with other management server clusters.

Once the high-level encryption policies (and other service policies) aredefined in the management plane, the management plane directly suppliessome or all of these policies to the management proxies (not shown) onthe hosts 200, and/or indirectly supplies some or all of these policiesto these proxies through a set of controllers (e.g., networkcontrollers). In some embodiments, the management proxies publish thereceived policies as rules to the context-based service rule storages140. In some embodiments, the proxies transform these policies beforepublishing them to the context-based service rule storages 140. Forinstance, in some embodiments, the policies are published with AppliedTotuples that identify the service nodes and/or logical networks to whichthey are associated. In some of these embodiments, the managementproxies on the hosts remove the AppliedTo tuple from each servicepolicy, before pushing the policy as a service rule to the service rulestorage 140. Also, as mentioned above, the context engines 110 on thehosts 200 in some embodiments resolve the policies based on collectedcontextual attributes, in order to generate rules for the serviceengines.

The process control (PC) engine 122 is a context-based PC engine thatperforms its PC operations based on PC rules that can be specified interms of contextual attributes. FIG. 19 illustrates several examples ofsuch PC rules. This figure illustrates a PC rule data store 140 of someembodiments. As shown, each PC rule includes a rule identifier 1905 anda PC action 1910. In some embodiments, a PC action 1910 can be (1)Allow, (2) Stop and Disallow, or (3) Stop and Terminate.

Each rule identifier 1905 specifies one or more data tuples that can beused to identify a rule that matches a data message flow. As shown, arule identifier can include contextual attributes, such as AppID,application name, application version, user ID, group ID, threat level,resource consumption, etc. In some embodiments, a PC engine searches aPC data storage by comparing one or more message attributes (e.g.,contextual attributes) with the rule identifiers 1905 to identify thehighest priority rule with a matching rule identifier. In someembodiments, the rule identifier 1905 can also include L2-L4 parameters(e.g., five tuple identifiers) associated with data message flows, andthe PC engine performs its PC operations on a per flow basis. In otherembodiments, the PC engine 122 only performs its PC operations forprocess events, and leaves it to the firewall engine 128 to perform PCoperations on a per flow basis. Accordingly, in some embodiments, therule identifiers 1905 of the PC rules for the PC engine do not includeany L2-L4 parameters.

In some embodiments, different PC engines 122 on different hosts enforcethe same set of PC rules. For instance, in some embodiments, differentPC engines 122 process the same PC rules on different hosts for VMs ofone logical network in order to provide a level of security on theprocesses running on these VMs. For this logical network, these PCengines 122 collectively form a distributed PC engine (i.e., a single,conceptual logical PC engine) that spans across the multiple hosts.

FIG. 19 illustrates three detailed examples of the context-based PCrules of some embodiments. The first rule 1920 specifies that SkypeVersion 1024 should be Stopped and Disallowed. In some embodiments, eachtime the PC engine 122 identifies a new process event, it identifies theevent's contextual attributes by interacting with the context engine orby examining the records in its attribute-mapping storage 223 toidentify a record that specifies the contextual attributes for theprocess identifier.

The second rule 1925 specifies that all processes that have a Highthreat level should be Stopped and Disallowed. As mentioned above, thecontext engine 110 or service engines 130 can interact with threatdetector 132 to assess the threat level associated with a process. Insome embodiments, the threat detector generates a threat score, whichthe context engine, PC engine, or the other service engines quantizeinto one of several categories. For example, in some embodiments, thethreat detector produces a threat score from 0 to 100, and one of theengines 110 or 130, designates scores between 0 and 33 to be a lowthreat level, designates scores between 34 and 66 to be a medium threatlevel, and designates scores between 67 and 100 to be a high threatlevel.

The third rule 1930 specifies that all processes that generate YouTubetraffic should be Stopped and Terminated. In some embodiments, this ruleis enforced by the PC engine, while in other embodiments, a similar ruleis enforced by the firewall engine. When the firewall engine enforcessuch a rule, it enforces this rule on a per flow basis and its action isto drop packets associated with this flow. The PC engine can enforcethis rule when checking a process event, or when it is called by the SFEport 260 to perform a PC check on a particular flow.

FIG. 20 illustrates a process 2000 that the PC engine 122 performs insome embodiments. As shown, the process 2000 starts when the PC enginereceives (at 2005) a process identifier from the context engine 110. Thecontext engine relays this process ID when it receives a processnotification from the GI agent 250 on a VM 205.

The process 2000 determines (at 2010) whether the connection state cache225 stores a record that identifies a PC action for the received processID. Each time a PC engine uses a PC rule to process a new processidentifier, the PC engine in some embodiments creates a record in theconnection state cache 225 to store the PC action performed so that itcan subsequently rely on this cache for faster processing of the sameprocess identifier. In some embodiments, each cached record in theconnection state cache 225 has a record identifier that is defined interms of process identifier. In these embodiments, the process comparesthe received identifier with the record identifiers of the cachedrecords to identify any record with a record identifier that matches thereceived process identifier.

When the process 2000 identifies (at 2010) a record for the receivedprocess event in the connection state cache 225, the process (at 2015)then performs the PC action specified in this record. When thisoperation is a disallowance or a termination, the PC engine directs thecontext engine 110 to disallow or terminate the process. To do this, thecontext engine 110 directs the GI agent that reported the event todisallow or terminate the process. The GI agent then directs the processsubsystem of the OS to disallow or terminate the process. After 2015,the process 2000 ends.

When the process 2000 determines (at 2010) that the connection statecache 225 does not store a record for the received process identifier,the process 2000 identifies (at 2020) one or more contextual attributesfor this process identifier. As mentioned above, the service engines ofdifferent embodiments perform this operation differently. In someembodiments, the PC engine directs the context engine to collectadditional process attributes for the received process event and thecontext engine collects this information by interacting with the GIagent.

Once the process 2000 has obtained the contextual attribute set for thereceived data message, it uses this attribute set to identify (at 2025)a PC rule in the PC rule data store 140. In some embodiments, the PCrules have rule identifiers 1505 that are defined in terms of one ormore contextual attributes, such as application name, applicationversion, user ID, group ID, AppID, threat level, resource consumptionlevel, etc. To identify the PC rule in the data store 140, the processin some embodiments compares the collected contextual attributes withthe rule identifiers (e.g., rule identifiers 1905) of the PC rules toidentify the highest priority rule that has an identifier that matchesthe collected attribute set.

When the process identifies a PC rule (at 2025), it performs the PCaction (e.g., Allow, Stop and Disallow, Stop and Terminate, etc.) ofthis rule on the received process event. When this operation is adisallowance or a termination, the PC engine directs the context engine110 to disallow or terminate the process. To do this, the context engine110 directs the GI agent that reported the event to disallow orterminate the process. The GI agent then directs the process subsystemof the OS to disallow or terminate the process. After performing the PCaction at 2030, the process creates (at 2035) a record in the connectionstate cache storage 225. This record identifies the PC action for thereceived process event. After 2035, the process ends.

As mentioned above, the management servers in some embodiments interactwith the discovery engines 120 executing on the hosts 200 in a datacenter to obtain and refresh inventory of all processes and servicesthat are running on the VMs on the hosts. The management plane in someembodiments then provides a rule creation interface for allowingadministrators to create context-based PC rules and/or policies for thePC engines 122 (as well as service rules for the other service engines130). The rule creation interface allows the administrators to definehigh-level PC policies (and other service policies) based onapplications inventoried through the data collected by the discoveryengines 120, and contextual attributes collected by the context engines110 and by the management plane's interface with other management serverclusters.

Once the high-level PC policies (and other service policies) are definedin the management plane, the management plane directly supplies some orall of these policies to the management proxies (not shown) on the hosts200, and/or indirectly supplies some or all of these policies to theseproxies through a set of controllers (e.g., network controllers). Insome embodiments, the management proxies publish the received policiesas rules to the context-based service rule storages 140. In someembodiments, the proxies transform these policies before publishing themto the context-based service rule storages 140. Also, as mentionedabove, the context engines 110 on the hosts 200 in some embodimentsresolve the policies based on collected contextual attributes, in orderto generate rules for the service engines.

FIG. 21 illustrates an example of how the service engines 130 aremanaged in some embodiments. This figure illustrates multiple hosts 200in a datacenter. As shown, each host includes several service engines130, a context engine 110, a threat detector 132, a DPI module 135,several VMs 205, and an SFE 210. It also illustrates a set ofcontrollers 2110 for managing the service engines 130, VMs 205, and SFEs210. As mentioned above, the context engines 110 in some embodimentscollect contextual attributes that are passed to the management serversin the controller set through a network 2150 (e.g., through a local areanetwork, a wide area network, a network of networks (such as theInternet), etc.). The controller set provides a user interface for theadministrators to define context-based service rules in terms of thesecollected contextual attributes, and communicates with the hosts throughthe network 2150 to provide these policies. The hosts alsocommunicatively connect to each other through this network 2150.

Many of the above-described features and applications are implemented assoftware processes that are specified as a set of instructions recordedon a computer readable storage medium (also referred to as computerreadable medium). When these instructions are executed by one or moreprocessing unit(s) (e.g., one or more processors, cores of processors,or other processing units), they cause the processing unit(s) to performthe actions indicated in the instructions. Examples of computer readablemedia include, but are not limited to, CD-ROMs, flash drives, RAM chips,hard drives, EPROMs, etc. The computer readable media does not includecarrier waves and electronic signals passing wirelessly or over wiredconnections.

In this specification, the term “software” is meant to include firmwareresiding in read-only memory or applications stored in magnetic storage,which can be read into memory for processing by a processor. Also, insome embodiments, multiple software inventions can be implemented assub-parts of a larger program while remaining distinct softwareinventions. In some embodiments, multiple software inventions can alsobe implemented as separate programs. Finally, any combination ofseparate programs that together implement a software invention describedhere is within the scope of the invention. In some embodiments, thesoftware programs, when installed to operate on one or more electronicsystems, define one or more specific machine implementations thatexecute and perform the operations of the software programs.

FIG. 22 conceptually illustrates a computer system 2200 with which someembodiments of the invention are implemented. The computer system 2200can be used to implement any of the above-described hosts, controllers,and managers. As such, it can be used to execute any of the abovedescribed processes. This computer system includes various types ofnon-transitory machine readable media and interfaces for various othertypes of machine readable media. Computer system 2200 includes a bus2205, processing unit(s) 2210, a system memory 2225, a read-only memory2230, a permanent storage device 2235, input devices 2240, and outputdevices 2245.

The bus 2205 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of thecomputer system 2200. For instance, the bus 2205 communicativelyconnects the processing unit(s) 2210 with the read-only memory 2230, thesystem memory 2225, and the permanent storage device 2235.

From these various memory units, the processing unit(s) 2210 retrieveinstructions to execute and data to process in order to execute theprocesses of the invention. The processing unit(s) may be a singleprocessor or a multi-core processor in different embodiments. Theread-only-memory (ROM) 2230 stores static data and instructions that areneeded by the processing unit(s) 2210 and other modules of the computersystem. The permanent storage device 2235, on the other hand, is aread-and-write memory device. This device is a non-volatile memory unitthat stores instructions and data even when the computer system 2200 isoff. Some embodiments of the invention use a mass-storage device (suchas a magnetic or optical disk and its corresponding disk drive) as thepermanent storage device 2235.

Other embodiments use a removable storage device (such as a floppy disk,flash drive, etc.) as the permanent storage device. Like the permanentstorage device 2235, the system memory 2225 is a read-and-write memorydevice. However, unlike storage device 2235, the system memory is avolatile read-and-write memory, such a random access memory. The systemmemory stores some of the instructions and data that the processor needsat runtime. In some embodiments, the invention's processes are stored inthe system memory 2225, the permanent storage device 2235, and/or theread-only memory 2230. From these various memory units, the processingunit(s) 2210 retrieve instructions to execute and data to process inorder to execute the processes of some embodiments.

The bus 2205 also connects to the input and output devices 2240 and2245. The input devices enable the user to communicate information andselect commands to the computer system. The input devices 2240 includealphanumeric keyboards and pointing devices (also called “cursor controldevices”). The output devices 2245 display images generated by thecomputer system. The output devices include printers and displaydevices, such as cathode ray tubes (CRT) or liquid crystal displays(LCD). Some embodiments include devices such as a touchscreen thatfunction as both input and output devices.

Finally, as shown in FIG. 22, bus 2205 also couples computer system 2200to a network 2265 through a network adapter (not shown). In this manner,the computer can be a part of a network of computers (such as a localarea network (“LAN”), a wide area network (“WAN”), or an Intranet, or anetwork of networks, such as the Internet. Any or all components ofcomputer system 2200 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in amachine-readable or computer-readable medium (alternatively referred toas computer-readable storage media, machine-readable media, ormachine-readable storage media). Some examples of such computer-readablemedia include RAM, ROM, read-only compact discs (CD-ROM), recordablecompact discs (CD-R), rewritable compact discs (CD-RW), read-onlydigital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a varietyof recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),magnetic and/or solid state hard drives, read-only and recordableBlu-Ray® discs, ultra-density optical discs, any other optical ormagnetic media, and floppy disks. The computer-readable media may storea computer program that is executable by at least one processing unitand includes sets of instructions for performing various operations.Examples of computer programs or computer code include machine code,such as is produced by a compiler, and files including higher-level codethat are executed by a computer, an electronic component, or amicroprocessor using an interpreter.

While the above discussion primarily refers to microprocessor ormulti-core processors that execute software, some embodiments areperformed by one or more integrated circuits, such as applicationspecific integrated circuits (ASICs) or field programmable gate arrays(FPGAs). In some embodiments, such integrated circuits executeinstructions that are stored on the circuit itself.

As used in this specification, the terms “computer”, “server”,“processor”, and “memory” all refer to electronic or other technologicaldevices. These terms exclude people or groups of people. For thepurposes of the specification, the terms display or displaying meansdisplaying on an electronic device. As used in this specification, theterms “computer readable medium,” “computer readable media,” and“machine readable medium” are entirely restricted to tangible, physicalobjects that store information in a form that is readable by a computer.These terms exclude any wireless signals, wired download signals, andany other ephemeral or transitory signals.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. For instance, several figuresconceptually illustrate processes. The specific operations of theseprocesses may not be performed in the exact order shown and described.The specific operations may not be performed in one continuous series ofoperations, and different specific operations may be performed indifferent embodiments. Furthermore, the process could be implementedusing several sub-processes, or as part of a larger macro process. Thus,one of ordinary skill in the art would understand that the invention isnot to be limited by the foregoing illustrative details, but rather isto be defined by the appended claims

We claim:
 1. A method for supporting context-based services on a hostcomputer on which a plurality of machines and a set of one or moreservice engines execute, the method comprising: at a context collectorexecuting on the host computer: collecting contextual attributes forevents occurring on a set of machines; providing sets of contextualattributes to the set of service engines for the service engines to useto process data message flows associated with the events, said providingcomprising (i) receiving data message flow identifiers from the set ofservice engines (ii) matching the data message flow identifiers tocollected contextual attribute sets stored by the context collector, and(iii) in response to the received data message flow identifiers,providing the matching contextual attribute sets to the set of serviceengines, each service engine using the contextual attribute sets toidentify service rules that specify service operations that the serviceengine has to perform on data message flows processed by the serviceengine; and generating a particular service rule for a particularservice engine for one of the events, the particular service engineusing the particular service rule to perform a service operation on atleast one data message flow.
 2. The method of claim 1, whereingenerating the particular service rule comprises directing theparticular service engine to generate the service rule.
 3. The method ofclaim 1, wherein generating the particular service rule comprisesgenerating the particular service rule at the context collector andproviding the generated service rule to the particular service engine.4. The method of claim 1, wherein the events comprise new networkconnection events.
 5. The method of claim 1, wherein the events comprisenew process events.
 6. The method of claim 1, wherein collecting thecontextual attribute sets comprises receiving at least a subset of thecontextual attribute sets from guest introspection agents executing ontwo or more machines.
 7. The method of claim 1, wherein collecting thecontextual attribute sets comprises receiving contextual attribute setswith identifiers of associated flows.
 8. The method of claim 1, whereineach of a plurality of sets of contextual attributes comprises one ormore attributes other than layer 2 (L2), layer 3 (L3) and layer 4 (L4)data-message header values.
 9. A method for supporting context-basedservices on a host computer on which a plurality of machines and a setof one or more service engines execute, the method comprising: at acontext collector executing on the host computer: collecting contextualattributes for events occurring on a set of machines; providing sets ofcontextual attributes to the set of service engines for the serviceengines to use to process data message flows associated with the events,wherein providing sets of contextual attributes comprises providing tothe set of service engines mapping records that map the collectedcontextual attribute sets with data message flow identifiers, eachservice engine matching identifiers of the data message flows that theservice engine processes with one or more mapping records in order toidentify contextual attribute sets associated with the processed datamessage flows, and using the identified contextual attributes sets toidentify service rules that specify service operations that the serviceengine has to perform on data message flows processed by the serviceengine; and generating a particular service rule for a particularservice engine for one of the events, the particular service engineusing the particular service rule to perform a service operation on atleast one data message flow.
 10. A non-transitory machine readablemedium storing a context collector program for supporting context-basedservices on a host computer on which a plurality of machines and a setof one or more service engines execute, the context collector programcomprising sets of instructions for: collecting contextual attributesfor events occurring on a set of machines; providing sets of contextualattributes to the set of service engines for the service engines to useto process data message flows associated with the events, wherein theset of instructions for providing sets of contextual attributescomprises sets of instructions for (i) receiving data message flowidentifiers from the set of service engines, (ii) matching the datamessage flow identifiers to collected contextual attribute sets storedby the context collector, and (iii) in response to the received datamessage flow identifiers, providing the matching contextual attributesets to the set of service engines, each service engine using thecontextual attribute sets to identify service rules that specify serviceoperations that the service engine has to perform on data message flowsprocessed by the service engine; and generating a particular servicerule for a particular service engine for one of the events, theparticular service engine using the particular service rule to perform aservice operation on at least one data message flow.
 11. Thenon-transitory machine readable medium of claim 10, wherein the set ofinstructions for generating the particular service rule comprises a setof instructions for directing the particular service engine to generatethe service rule.
 12. The non-transitory machine readable medium ofclaim 10, wherein the set of instructions for generating the particularservice rule comprises sets of instructions for generating theparticular service rule at the context collector and providing thegenerated service rule to the particular service engine.
 13. Thenon-transitory machine readable medium of claim 10, wherein the eventscomprise new network connection events.
 14. The non-transitory machinereadable medium of claim 10, wherein the events comprise new processevents.
 15. The non-transitory machine readable medium of claim 10,wherein the set of instructions for collecting the contextual attributesets comprises a set of instructions for receiving at least a subset ofthe contextual attribute sets from guest introspection agents executingon two or more machines.
 16. The non-transitory machine readable mediumof claim 10, wherein the set of instructions for collecting thecontextual attribute sets comprises a set of instructions for receivingcontextual attribute sets with identifiers of associated flows.
 17. Thenon-transitory machine readable medium of claim 10, wherein each of aplurality of sets of contextual attributes comprises one or moreattributes other than layer 2 (L2), layer 3 (L3) and layer 4 (L4)data-message header values.
 18. A non-transitory machine readable mediumstoring a context collector program for supporting context-basedservices on a host computer on which a plurality of machines and a setof one or more service engines execute, the context collector programcomprising sets of instructions for: collecting contextual attributesfor events occurring on a set of machines; providing sets of contextualattributes to the set of service engines for the service engines to useto process data message flows associated with the events, wherein theset of instructions for providing sets of contextual attributescomprises a set of instructions for providing to the set of serviceengines mapping records that map the collected contextual attribute setswith data message flow identifiers, each service engine matchingidentifiers of the data message flows that the service engine processeswith one or more mapping records in order to identify contextualattribute sets associated with the processed data message flows, andusing the identified contextual attributes sets to identify servicerules that specify service operations that the service engine has toperform on data message flows processed by the service engine; andgenerating a particular service rule for a particular service engine forone of the events, the particular service engine using the particularservice rule to perform a service operation on at least one data messageflow.